Showing 1–50 of 75 results for author: Deng, L

Closeby Habitable Exoplanet Survey (CHES). V. Planetary Parameters Derived from Angular Separation Variations

Authors: Dongjie Tan, Jianghui Ji, Chunhui Bao, Xiumin Huang, Guo Chen, Su Wang, Yao Dong, Jiacheng Liu, Zi Zhu, Haitao Li, Junbo Zhang, Liang Fang, Dong Li, Lei Deng

Abstract: The Closeby Habitable Exoplanet Survey (CHES) aims to achieve microarcsecond-level astrometry of about one hundred nearby FGK-type stars within 10 parsecs to detect Earth-like planets. Such precision exceeds the capability of absolute astrometry relying on Gaia catalogs, whose positional accuracy degrades over time due to error propagation from stellar motion and epoch offsets, limiting their use… ▽ More The Closeby Habitable Exoplanet Survey (CHES) aims to achieve microarcsecond-level astrometry of about one hundred nearby FGK-type stars within 10 parsecs to detect Earth-like planets. Such precision exceeds the capability of absolute astrometry relying on Gaia catalogs, whose positional accuracy degrades over time due to error propagation from stellar motion and epoch offsets, limiting their use in microarcsecond-level detection. Traditional relative astrometry depends on positional components along right ascension and declination, requiring precise knowledge of field rotation and satellite attitude, which introduces additional errors. To address this, we propose a new relative measurement model based solely on variations in the length of angular separation between the target and reference stars, independent of direction. The model incorporates effects such as proper motion, parallax, radial velocity, light aberration, gravitational lensing, and planetary perturbations, enabling reconstruction of planetary orbits and masses. This approach enhances measurement stability and precision, providing a framework that is not entirely dependent on the Gaia catalog and suitable for CHES and other future high-accuracy astrometric missions. △ Less

Submitted 29 March, 2026; originally announced March 2026.

Comments: 20 pages, 7 figures, accepted to Research in Astronomy and Astrophysics

Permutation invariant multi-scale full quantum neural network wavefunction

Authors: Pengzhen Cai, Yubing Qian, Li Deng, Weizhong Fu, Lei Yang, Zhiyu Sun, Xin-Zheng Li, En-Ge Wang, Liangwen Chen, Weiluo Ren, Ji Chen

Abstract: Solving the intricate quantum behavior of interacting particles is key to unlocking the mysteries of condensed matter, but capturing their complex correlations across different scales remains a monumental challenge. We introduce a neural network framework that overcomes this barrier by modeling the full quantum wavefunction of a system, including electrons, nuclei and muons, directly capturing the… ▽ More Solving the intricate quantum behavior of interacting particles is key to unlocking the mysteries of condensed matter, but capturing their complex correlations across different scales remains a monumental challenge. We introduce a neural network framework that overcomes this barrier by modeling the full quantum wavefunction of a system, including electrons, nuclei and muons, directly capturing the full quantum effects beyond the Born-Oppenheimer approximation. The neural network approximates joint wavefunction of different interacting particles with a rigorous handling of permutation invariance, enabling simultaneous treatment of nuclear quantum effects and electron-nucleus-muon couplings without explicit excited states. Validated on molecular systems, this approach offers a computationally feasible way to model full quantum phenomena in complex many-body systems, establishing a direct connection between fundamental particle properties and emergent material behavior. △ Less

Submitted 12 March, 2026; originally announced March 2026.

Unsupervised dimensionality reduction of polarimetric data for pixel-wise pathological tissue differentiation

Authors: Mickaël Li, Nan Zeng, Liangyu Deng, Mingzhou Jiang, Chang Wu, Honghui He

Abstract: Extracellular matrix (ECM) constitutes a key basement structure to human organisms by acting as a complex network of large proteins and carbohydrates that provide structural support to surrounding cells. Remodeling in the extracellular matrix's structural fibers leads to insight into the development of diseases such as cancer, fibrosis and carcinoma. While standard tissues visualization in the ECM… ▽ More Extracellular matrix (ECM) constitutes a key basement structure to human organisms by acting as a complex network of large proteins and carbohydrates that provide structural support to surrounding cells. Remodeling in the extracellular matrix's structural fibers leads to insight into the development of diseases such as cancer, fibrosis and carcinoma. While standard tissues visualization in the ECM involves multiple lengthy histopathological staining protocols, Mueller matrix-based polarimetry provides label-free tissue slices' microstructural information and optical properties. This work aims to identify three types of fiber tissues commonly found in the ECM of gastrointestinal tissue specimens by analyzing their polarization properties. To address decomposition methods' reliance on restrictive hypotheses and inability with an individual polarization-based parameter to determine the nature of a given biological tissue; this study employs Uniform Manifold Approximation and Projection (UMAP) method to offer greater discriminative power and flexibility. Subsequently, polarization-based features will be extracted and compared between fiber regions statistically to discern potential diagnostic differences. By providing colorized images, this work aims to demonstrate the feasibility of distinguishing different fibers with polarization approach, offering insights for future clinical development while complementing existing staining methods for pathological tissue specimens. △ Less

Submitted 15 February, 2026; originally announced February 2026.

The Solar Close Observations and Proximity Experiments (SCOPE) mission

Authors: Jun Lin, Jing Feng, Zhenhua Ge, Jiang Tian, Yuhao Chen, Xin Cheng, Hui Tian, Jiansen He, Alexei Pevtsov, Haisheng Ji, Shangbin Yang, Parida Hashim, Bin Zhou, Yiteng Zhang, Shenyi Zhang, Xi Lu, Yuan Yuan, Liu Liu, Haoyu Wang, Hu Jiang, Lei Deng, Xingjian Shi, Lin Ma, Jingxing Wang, Shanjie Huang , et al. (9 additional authors not shown)

Abstract: The Solar Close Observations and Proximity Experiments (SCOPE) mission will send a spacecraft into the solar atmosphere at a low altitude of just 5 R_sun from the solar center. It aims to elucidate the mechanisms behind solar eruptions and coronal heating, and to directly measure the coronal magnetic field. The mission will perform in situ measurements of the current sheet between coronal mass eje… ▽ More The Solar Close Observations and Proximity Experiments (SCOPE) mission will send a spacecraft into the solar atmosphere at a low altitude of just 5 R_sun from the solar center. It aims to elucidate the mechanisms behind solar eruptions and coronal heating, and to directly measure the coronal magnetic field. The mission will perform in situ measurements of the current sheet between coronal mass ejections and their associated solar flares, and energetic particles produced by either reconnection or fast-mode shocks driven by coronal mass ejections. This will help to resolve the nature of reconnections in current sheets, and energetic particle acceleration regions. To investigate coronal heating, the mission will observe nano-flares on scales smaller than 70 km in the solar corona and regions smaller than 40 km in the photosphere, where magnetohydrodynamic waves originate. To study solar wind acceleration mechanisms, the mission will also track the process of ion charge-state freezing in the solar wind. A key achievement will be the observation of the coronal magnetic field at unprecedented proximity to the solar photosphere. The polar regions will also be observed at close range, and the inner edge of the solar system dust disk may be identified for the first time. This work presents the detailed background, science, and mission concept of SCOPE and discusses how we aim to address the questions mentioned above. △ Less

Submitted 27 November, 2025; originally announced November 2025.

Comments: 27 pages, 15 figures

Journal ref: Astronomical Techniques and Instruments, 2(3), 2025

Generalized Gauss-Jacobi rules for discrete velocity method in Multiscale Flow Simulations

Authors: Lu Wang, Lingyun Deng, Guanqing Wang, Hong Liang, Jiangrong Xu

Abstract: The discrete velocity method (DVM) is a powerful framework for simulating gas flows across continuum to rarefied regimes, yet its efficiency remains limited by existing quadrature rules. Conventional infinite-domain quadratures, such as Gauss-Hermite, distribute velocity nodes globally and perform well near equilibrium but fail under strong nonequilibrium conditions. In contrast, finite-interval q… ▽ More The discrete velocity method (DVM) is a powerful framework for simulating gas flows across continuum to rarefied regimes, yet its efficiency remains limited by existing quadrature rules. Conventional infinite-domain quadratures, such as Gauss-Hermite, distribute velocity nodes globally and perform well near equilibrium but fail under strong nonequilibrium conditions. In contrast, finite-interval quadratures, such as Newton-Cotes, enable local refinement but lose efficiency near equilibrium. To overcome these limitations, we propose a generalized Gauss-Jacobi quadrature (GGJQ) for DVM, built upon a new class of adjustable weight functions. This framework systematically constructs one- to three-dimensional quadratures and maps the velocity space into polar or spherical coordinates, enabling flexible and adaptive discretization. The GGJQ accurately captures both near-equilibrium and highly rarefied regimes, as well as low- and high-Mach flows, achieving superior computational efficiency without compromising accuracy. Numerical experiments over a broad range of Knudsen numbers confirm that GGJQ consistently outperforms traditional Newton-Cotes and Gauss-Hermite schemes, offering a robust and efficient quadrature strategy for multiscale kinetic simulations. △ Less

Submitted 22 October, 2025; originally announced October 2025.

Comments: 24 pages, 20 figures

Airway Mucus Rheology: Physical Insights for Navigating through Health to Pathology and Clinical Applications

Authors: Zhiwei Liu, Bo Che, Hailin Zhang, Linhong Deng

Abstract: Airway mucus is a complex gel with an anisotropic three-dimensional network structure. As a crucial component of the respiratory defense barrier, it plays a vital role in maintaining airway hydration and supporting the function of airway epithelial cells. Through linear and nonlinear rheological mechanisms such as ciliary motion and coughing, airway mucus expels foreign pathogens and toxic nano- a… ▽ More Airway mucus is a complex gel with an anisotropic three-dimensional network structure. As a crucial component of the respiratory defense barrier, it plays a vital role in maintaining airway hydration and supporting the function of airway epithelial cells. Through linear and nonlinear rheological mechanisms such as ciliary motion and coughing, airway mucus expels foreign pathogens and toxic nano- and microparticles while selectively allowing the passage of specific nutrients and proteins. These protective and clearance functions depend on the proper rheological properties of mucus under normal physiological conditions. However, in respiratory disease such as CF, COPD, asthma, and COVID-19, excessive mucus secretion is often accompanied by abnormal rheological behaviors. This leads to impaired mucus flow, airway obstruction, and potentially life-threatening conditions. Therefore, this review examines the rheological behaviors of airway mucus in relation to health and disease, focusing on both macrorheology and microrheology. The review highlights those changes in the chemical composition and microstructure of airway mucus, especially under pathological conditions, that can significantly alter its rheological behavior. Rheological parameters can also serve as biological indicators to study the role of mucus in clearance functions and aid in developing pulmonary drug delivery systems. By integrating findings from both macro- and microrheological studies, this review aims to enhance our understanding of the complex behavior of airway mucus, supporting better diagnosis, treatment, and management of chronic respiratory diseases. △ Less

Submitted 17 October, 2025; originally announced October 2025.

Improving Muon Scattering Tomography Performance With A Muon Momentum Measurement Scheme

Authors: Pei Yu, Ziwen Pan, Jiajia Zhai, Yu Xu, Li Deng, Zhengyang He, Zhe Chen, Zechao Kang, Yuhong Yu, Xueheng Zhang, Liangwen Chen, Lei Yang, Zhiyu Sun

Abstract: Muon imaging, especially muon scattering tomography (MST), has recently garnered significant attention. MST measures the magnitude of muon scattering angles inside an object, which depends not only on the material properties but also on the muon momentum. Due to the difficulty of simultaneous measurement of momentum, it was neglected and taken as a constant in multiple MST reconstruction algorithm… ▽ More Muon imaging, especially muon scattering tomography (MST), has recently garnered significant attention. MST measures the magnitude of muon scattering angles inside an object, which depends not only on the material properties but also on the muon momentum. Due to the difficulty of simultaneous measurement of momentum, it was neglected and taken as a constant in multiple MST reconstruction algorithms. Recently, an experimental measurement scheme has emerged that is feasible in engineering, but it requires many layers of detectors to approach the true momentum. From this, we proposed both an algorithm to incorporating momentum into MST, and a scheme to determine the thresholds of Cherenkov detectors. This novel scheme, termed the "equi-percentage scheme", sets momentum thresholds for Cherenkov detector layers based on cosmic muon momentum distribution. Results showed our approach delivers noticeable enhancement in reconstructed image quality even with only two detector layers, reaching near-saturation performance with four layers. This study proves that momentum measurement significantly enhances short-duration MST, and that substantial improvement can be achieved with relatively coarse momentum measurement using 2-4 layers of Cherenkov detectors. △ Less

Submitted 16 September, 2025; originally announced September 2025.

Unlock giant nonreciprocity via multi-valued behavior of non-Hermitian zero-index materials

Authors: Yang Li, Yueyang Liu, Yucong Yang, Tianyi Zhang, Jianfeng Chen, Tian Dong, Fulong Shi, Phatham Loahavilai, Tianchi Zhang, Di Wu, Zixuan Wei, Dengfu Deng, Jun Qin, Longjiang Deng, Cheng-Wei Qiu, Lei Bi

Abstract: Although Einstein's field equations are time-independent, the multivalued feature of the horizon of a blackhole naturally enables the one-way transmission, leading to the strong arrow of time from the time-independent gravitational interaction. Here we experimentally demonstrate a photonic analogue of this principle and reveal the infinite nonreciprocity of the time-reversal-symmetric Maxwell equa… ▽ More Although Einstein's field equations are time-independent, the multivalued feature of the horizon of a blackhole naturally enables the one-way transmission, leading to the strong arrow of time from the time-independent gravitational interaction. Here we experimentally demonstrate a photonic analogue of this principle and reveal the infinite nonreciprocity of the time-reversal-symmetric Maxwell equations. By designing a non-Hermitian zero-index magneto-optical metawaveguide, we introduce multivalued feature to this metawaveguide's complex eigenspace via an exceptional point with non-zero residue, bringing nonlocal, path-dependent historical memory to the system. Hence, a weak magneto-optical response can direct forward and backward waves to two photonic branches with largely distinct momenta and losses, leading to the optical nonreciprocity far beyond the limitation imposed by the magneto-optical material. We fabricated an a-Si/Ce:YIG metawaveguide, achieving nonreciprocal phase shift of 47.78 rad/mm and nonreciprocal loss of 53.9 dB/mm near 1575 nm, exceeding state-of-the-art nonreciprocal devices by an order of magnitude. Our principle universally applies from microwave to visible frequencies, leading to compact isolators, circulators, and sensors. Our principle can also be extended to nonreciprocal acoustic, elastic, and thermal systems. The proposed new paradigm -- geometry-based strong arrow of time in covariant and reversible physical systems -- has broad implications in many disciplines including string theory, cosmology, and astronomy. △ Less

Submitted 7 September, 2025; originally announced September 2025.

Comments: 24 pages, 5 figures

All-optical discrete illumination-based compressed ultrafast photography

Authors: Long Cheng, Dalong Qi, Jiali Yao, Ning Xu, Chengyu Zhou, Wenzhang Lin, Yu He, Zhen Pan, Yunhua Yao, Lianzhong Deng, Yuecheng Shen, Zhenrong Sun, Shian Zhang

Abstract: Snapshot ultrafast optical imaging (SUOI) plays a vital role in capturing complex transient events in real time, with significant implications for both fundamental science and practical applications. As an outstanding talent in SUOI, compressed ultrafast photography (CUP) has demonstrated remarkable frame rate reaching trillions of frames per second and hundreds of sequence depth. Nevertheless, as… ▽ More Snapshot ultrafast optical imaging (SUOI) plays a vital role in capturing complex transient events in real time, with significant implications for both fundamental science and practical applications. As an outstanding talent in SUOI, compressed ultrafast photography (CUP) has demonstrated remarkable frame rate reaching trillions of frames per second and hundreds of sequence depth. Nevertheless, as CUP relies on streak cameras, the system's imaging fidelity suffers from an inevitable limitation induced by the charge coupling artifacts in a streak camera. Moreover, although advanced image reconstruction algorithms have improved the recovered scenes, its high compression ratio still causes a compromise in image quality. To address these challenges, we propose a novel approach termed all-optical discrete illumination compressed ultrafast photography (AOD-CUP), which employs a free-space angular-chirp-enhanced delay (FACED) technique to temporally stretch femtosecond pulses and achieves discrete illumination for dynamic scenes. With its distinctive system architecture, AOD-CUP features adjustable frame numbers and flexible inter-frame intervals ranging from picoseconds to nanoseconds, thereby achieving high-fidelity ultrafast imaging in a snapshot. Experimental results demonstrate the system's superior dynamic spatial resolution and its capability to visualize ultrafast phenomena with complex spatial details, such as stress wave propagation in LiF crystals and air plasma channel formation. These results highlight the potential of AOD-CUP for high-fidelity, real-time ultrafast imaging, which provides an unprecedented tool for advancing the frontiers of ultrafast science. △ Less

Submitted 27 May, 2025; originally announced May 2025.

Thermal Conductivity above 2000 W/m.K in Boron Arsenide by Nanosecond Transducer-less Time-Domain Thermoreflectance

Authors: Hong Zhong, Ying Peng, Feng Lin, Ange Benise Niyikiza, Fengjiao Pan, Chengzhen Qin, Jinghong Chen, Viktor G. Hadjiev, Liangzi Deng, Zhifeng Ren, Jiming Bao

Abstract: Cubic boron arsenide (c-BAs) has been theoretically predicted to exhibit thermal conductivity \k{appa} comparable to that of diamond, yet experimental measurements have plateaued at ~1300W/mK. We report room-temperature \k{appa} exceeding 2000W/mK in c-BAs, on par with single-crystal diamond. This finding is enabled by high-quality single crystals and a newly developed nanosecond, transducer-less… ▽ More Cubic boron arsenide (c-BAs) has been theoretically predicted to exhibit thermal conductivity \k{appa} comparable to that of diamond, yet experimental measurements have plateaued at ~1300W/mK. We report room-temperature \k{appa} exceeding 2000W/mK in c-BAs, on par with single-crystal diamond. This finding is enabled by high-quality single crystals and a newly developed nanosecond, transducer-less time-domain thermoreflectance technique that allows spatial mapping of \k{appa} without metal transducers. Thermal conductivity correlates with crystal quality, as evidenced by stronger photoluminescence and longer photoluminescence lifetimes. However, the observed nanosecond lifetimes remain shorter than expected for an indirect bandgap semiconductor, suggesting room for further crystal quality improvement and higher \k{appa}. These results challenge current theoretical models and highlight c-BAs as a promising material for next-generation electronics. △ Less

Submitted 23 May, 2025; originally announced May 2025.

Comments: 14 pages, 4 figures

Transfer learning empowers material Z classification with muon tomography

Authors: Haochen Wang, Zhao Zhang, Pei Yu, Yuxin Bao, Jiajia Zhai, Yu Xu, Li Deng, Sa Xiao, Xueheng Zhang, Yuhong Yu, Weibo He, Liangwen Chen, Yu Zhang, Lei Yang, Zhiyu Sun

Abstract: Cosmic-ray muon sources exhibit distinct scattering angle distributions when interacting with materials of different atomic numbers (Z values), facilitating the identification of various Z-class materials, particularly those radioactive high-Z nuclear elements. Most of the traditional identification methods are based on complex muon event reconstruction and trajectory fitting processes. Supervised… ▽ More Cosmic-ray muon sources exhibit distinct scattering angle distributions when interacting with materials of different atomic numbers (Z values), facilitating the identification of various Z-class materials, particularly those radioactive high-Z nuclear elements. Most of the traditional identification methods are based on complex muon event reconstruction and trajectory fitting processes. Supervised machine learning methods offer some improvement but rely heavily on prior knowledge of target materials, significantly limiting their practical applicability in detecting concealed materials. For the first time, transfer learning is introduced into the field of muon tomography in this work. We propose two lightweight neural network models for fine-tuning and adversarial transfer learning, utilizing muon tomography data of bare materials to predict the Z-class of coated materials. By employing the inverse cumulative distribution function method, more accurate scattering angle distributions could be obtained from limited data, leading to an improvement by nearly 4\% in prediction accuracy compared with the traditional random sampling based training. When applied to coated materials with limited labeled or even unlabeled muon tomography data, the proposed method achieves an overall prediction accuracy exceeding 96\%, with high-Z materials reaching nearly 99\%. Simulation results indicate that transfer learning improves prediction accuracy by approximately 10\% compared to direct prediction without transfer. This study demonstrates the effectiveness of transfer learning in overcoming the physical challenges associated with limited labeled/unlabeled data, highlights the promising potential of transfer learning in the field of muon tomography. △ Less

Submitted 1 April, 2025; originally announced April 2025.

The Feasibility Study of the GeV-Energy Muon Source Based on HIAF

Authors: Yu Xu, Xueheng Zhang, Yuhong Yu, Pei Yu, Li Deng, Jiajia Zhai, Liangwen Chen, He Zhao, Lina Sheng, Guodong Shen, Ziwen Pan, Qite Li, Chen Zhou, Qiang Li, Lei Yang, Zhiyu Sun

Abstract: Generating a mono-energetic, high-energy muon beam using accelerator facilities can be very attractive for many purposes, for example, improving muon tomography currently limited by the low flux and wide energy spread of cosmic ray muons, and searching for muon related new physics beyond the Standard Model. One potential accelerator facility is the High Intensity Heavy-Ion Accelerator Facility (HI… ▽ More Generating a mono-energetic, high-energy muon beam using accelerator facilities can be very attractive for many purposes, for example, improving muon tomography currently limited by the low flux and wide energy spread of cosmic ray muons, and searching for muon related new physics beyond the Standard Model. One potential accelerator facility is the High Intensity Heavy-Ion Accelerator Facility (HIAF), which is currently under construction in Huizhou City, China. Considering the projectile energy and beamline length, a high-intensity and GeV-energy muon flux could be produced and delivered by the High Energy Fragment Separator beamline of the HIAF facility. In this paper, the flux intensity and purity of muon beam based on HIAF are discussed in detail. For the $μ^+$ beam, the highest muon yield reaches $8.2 \times 10^6 ~ μ$/s with the purity of approximately $2\%$ at a momentum of 3.5 GeV/c; meanwhile, for the $μ^-$ beam, the maximum muon yield is 4.2 $\times 10^6 ~ μ$/s with the purity of around $20\%$ at a momentum of 1.5 GeV/c. The results also indicate that, for muon beams with an energy of several GeV, by applying a suitable purification strategy, we can get a muon beam with a purity of 100\% and an intensity of the order of $10^5 ~ μ$/s. △ Less

Submitted 21 May, 2025; v1 submitted 28 February, 2025; originally announced February 2025.

Comments: 12 pages, accepted for publication in the PHYSICAL REVIEW ACCELERATORS AND BEAMS

An Evolutionary Game With the Game Transitions Based on the Markov Process

Authors: Minyu Feng, Bin Pi, Liang-Jian Deng, Jürgen Kurths

Abstract: The psychology of the individual is continuously changing in nature, which has a significant influence on the evolutionary dynamics of populations. To study the influence of the continuously changing psychology of individuals on the behavior of populations, in this paper, we consider the game transitions of individuals in evolutionary processes to capture the changing psychology of individuals in… ▽ More The psychology of the individual is continuously changing in nature, which has a significant influence on the evolutionary dynamics of populations. To study the influence of the continuously changing psychology of individuals on the behavior of populations, in this paper, we consider the game transitions of individuals in evolutionary processes to capture the changing psychology of individuals in reality, where the game that individuals will play shifts as time progresses and is related to the transition rates between different games. Besides, the individual's reputation is taken into account and utilized to choose a suitable neighbor for the strategy updating of the individual. Within this model, we investigate the statistical number of individuals staying in different game states and the expected number fits well with our theoretical results. Furthermore, we explore the impact of transition rates between different game states, payoff parameters, the reputation mechanism, and different time scales of strategy updates on cooperative behavior, and our findings demonstrate that both the transition rates and reputation mechanism have a remarkable influence on the evolution of cooperation. Additionally, we examine the relationship between network size and cooperation frequency, providing valuable insights into the robustness of the model. △ Less

Submitted 8 February, 2025; originally announced February 2025.

First Proof of Principle Experiment for Muon Production with Ultrashort High Intensity Laser

Authors: Feng Zhang, Li Deng, Yanjie Ge, Jiaxing Wen, Bo Cui, Ke Feng, Hao Wang, Chen Wu, Ziwen Pan, Hongjie Liu, Zhigang Deng, Zongxin Zhang, Liangwen Chen, Duo Yan, Lianqiang Shan, Zongqiang Yuan, Chao Tian, Jiayi Qian, Jiacheng Zhu, Yi Xu, Yuhong Yu, Xueheng Zhang, Lei Yang, Weimin Zhou, Yuqiu Gu , et al. (4 additional authors not shown)

Abstract: Muons, which play a crucial role in both fundamental and applied physics, have traditionally been generated through proton accelerators or from cosmic rays. With the advent of ultra-short high-intensity lasers capable of accelerating electrons to GeV levels, it has become possible to generate muons in laser laboratories. In this work, we show the first proof of principle experiment for novel muon… ▽ More Muons, which play a crucial role in both fundamental and applied physics, have traditionally been generated through proton accelerators or from cosmic rays. With the advent of ultra-short high-intensity lasers capable of accelerating electrons to GeV levels, it has become possible to generate muons in laser laboratories. In this work, we show the first proof of principle experiment for novel muon production with an ultra-short, high-intensity laser device through GeV electron beam bombardment on a lead converter target. The muon physical signal is confirmed by measuring its lifetime which is the first clear demonstration of laser-produced muons. Geant4 simulations were employed to investigate the photo-production, electro-production, and Bethe-Heitler processes response for muon generation and their subsequent detection. The results show that the dominant contributions of muons are attributed to the photo-production/electro-production and a significant yield of muons up to 0.01 $μ$/$e^-$ out of the converter target could be achieved. This laser muon source features compact, ultra-short pulse and high flux. Moreover, its implementation in a small laser laboratory is relatively straightforward, significantly reducing the barriers to entry for research in areas such as muonic X-ray elemental analysis, muon spin spectroscopy and so on. △ Less

Submitted 31 October, 2024; originally announced October 2024.

Journal ref: Nature Physics,21,1050, 2025

The cloud cover and meteorological parameters at the Lenghu site on the Tibetan Plateau

Authors: Ruiyue Li, Fei He, Licai Deng, Xiaodian Chen, Fan Yang, Yong Zhao, Bo Zhang, Chunguang Zhang, Chen Yang, Tian Lan

Abstract: The cloud cover and meteorological parameters serve as fundamental criteria for the qualification of an astronomical observatory working in optical and infrared wavelengths. In this paper, we present a systematic assessment of key meteorological parameters at the Lenghu site. The datasets adopted in this study includes the meteorological parameters collected at the local weather stations at the si… ▽ More The cloud cover and meteorological parameters serve as fundamental criteria for the qualification of an astronomical observatory working in optical and infrared wavelengths. In this paper, we present a systematic assessment of key meteorological parameters at the Lenghu site. The datasets adopted in this study includes the meteorological parameters collected at the local weather stations at the site and in the Lenghu Town, the sky brightness at the local zenith acquired by the Sky Quality Meters and night sky all-sky images from a digital camera, the ERA5 reanalysis database and global climate monitoring data. From 2019 to 2023, the fractional observable time of photometric condition is 69.70%, 74.97%, 70.26%, 74.27% and 65.12%, respectively. The fractional observing time is inversely correlated with surface air temperature, relative humidity, precipitable water vapor, and dew temperature, demonstrating that the observing conditions are influenced by these meteorological parameters. Large-scale air-sea interactions affect the climate at Lenghu site, which in fact delivers a clue to understand the irregularity of 2023. Specifically, precipitable water vapor at Lenghu site is correlated to both the westerly wind index and the summer North Atlantic Oscillation index, the yearly average temperature of Lenghu site is observed to increase significantly during the occurrence of a strong El Niño event and the relative humidity anomaly at Lenghu site is correlated to the Pacific Decadal Oscillation index. The decrease of fractional observing time in 2023 was due to the ongoing strong El Niño event and relevant global climate change. We underscore the substantial role of global climate change in regulating astronomical observing conditions and the necessity for long-term continuous monitoring of the astronomical meteorological parameters at Lenghu site. △ Less

Submitted 17 October, 2024; originally announced October 2024.

Comments: accepted for publication in MNRAS

Improving Typhoon Predictions by Integrating Data-Driven Machine Learning Models with Physics Models Based on the Spectral Nudging and Data Assimilation

Authors: Zeyi Niu, Wei Huang, Lei Zhang, Lin Deng, Haibo Wang, Yuhua Yang, Dongliang Wang, Hong Li

Abstract: With the rapid development of data-driven machine learning (ML) models in meteorology, typhoon track forecasts have become increasingly accurate. However, current ML models still face challenges, such as underestimating typhoon intensity and lacking interpretability. To address these issues, this study establishes an ML-driven hybrid typhoon model, where forecast fields from the Pangu-Weather mode… ▽ More With the rapid development of data-driven machine learning (ML) models in meteorology, typhoon track forecasts have become increasingly accurate. However, current ML models still face challenges, such as underestimating typhoon intensity and lacking interpretability. To address these issues, this study establishes an ML-driven hybrid typhoon model, where forecast fields from the Pangu-Weather model are used to constrain the large-scale forecasts of the Weather Research and Forecasting model based on the spectral nudging method (Pangu_SP). The results show that forecasts from the Pangu_SP experiment obviously outperform those by using the Global Forecast System as the initial field (GFS_INIT) and from the Integrated Forecasting System of the European Centre for Medium-Range Weather Forecasts (ECMWF IFS) for the track forecast of Typhoon Doksuri (2023). The predicted typhoon cloud patterns from Pangu_SP are also more consistent with satellite observations. Additionally, the typhoon intensity forecasts from Pangu_SP are notably more accurate than those from the ECMWF IFS, demonstrating that the hybrid model effectively leverages the strengths of both ML and physical models. Furthermore, this study is the first to explore the significance of data assimilation in ML-driven hybrid dynamical systems. The findings reveal that after assimilating water vapor channels from the Advanced Geostationary Radiation Imager onboard Fengyun-4B, the errors in typhoon intensity forecasts are reduced. △ Less

Submitted 22 August, 2024; originally announced August 2024.

Comments: 12 pages, 4 figures

A Strategy Transfer and Decision Support Approach for Epidemic Control in Experience Shortage Scenarios

Authors: X. Xiao, P. Chen, X. Cao, K. Liu, L. Deng, D. Zhao, Z. Chen, Q. Deng, F. Yu, H. Zhang

Abstract: Epidemic outbreaks can cause critical health concerns and severe global economic crises. For countries or regions with new infectious disease outbreaks, it is essential to generate preventive strategies by learning lessons from others with similar risk profiles. A Strategy Transfer and Decision Support Approach (STDSA) is proposed based on the profile similarity evaluation. There are four steps in… ▽ More Epidemic outbreaks can cause critical health concerns and severe global economic crises. For countries or regions with new infectious disease outbreaks, it is essential to generate preventive strategies by learning lessons from others with similar risk profiles. A Strategy Transfer and Decision Support Approach (STDSA) is proposed based on the profile similarity evaluation. There are four steps in this method: (1) The similarity evaluation indicators are determined from three dimensions, i.e., the Basis of National Epidemic Prevention & Control, Social Resilience, and Infection Situation. (2) The data related to the indicators are collected and preprocessed. (3) The first round of screening on the preprocessed dataset is conducted through an improved collaborative filtering algorithm to calculate the preliminary similarity result from the perspective of the infection situation. (4) Finally, the K-Means model is used for the second round of screening to obtain the final similarity values. The approach will be applied to decision-making support in the context of COVID-19. Our results demonstrate that the recommendations generated by the STDSA model are more accurate and aligned better with the actual situation than those produced by pure K-means models. This study will provide new insights into preventing and controlling epidemics in regions that lack experience. △ Less

Submitted 9 April, 2024; originally announced April 2024.

Comments: 20 pages, 9 figures

Polarization-Encoded Lenticular Nano-Printing with Single-Layer Metasurfaces

Authors: Lin Deng, Ziqiang Cai, Yongmin Liu

Abstract: Metasurface-based nano-printing has enabled ultrahigh-resolution grayscale or color image display. However, the maximum number of independent nano-printing images allowed by one single-layer metasurface is still limited despite many multiplexing methods that have been proposed to increase the design degree of freedom. In this work, we substantially push the multiplexing limit of nano-printing by t… ▽ More Metasurface-based nano-printing has enabled ultrahigh-resolution grayscale or color image display. However, the maximum number of independent nano-printing images allowed by one single-layer metasurface is still limited despite many multiplexing methods that have been proposed to increase the design degree of freedom. In this work, we substantially push the multiplexing limit of nano-printing by transforming images at different observation angles into mapping the corresponding images to different positions in the Fourier space, and simultaneously controlling the complex electric field across multiple polarization channels. Our proposed Polarization-Encoded Lenticular Nano-Printing (Pollen), aided by a modified evolutionary algorithm, allows the display of several images based on the viewing angle, similar to traditional lenticular printing but without requiring a lenticular layer. In addition, it extends the display capability to encompass multiple polarization states. Empowered by the ability to control the complex amplitude of three polarization channels, we numerically and experimentally demonstrate the generation of 13 distinguished gray-scale Chinese ink wash painting images, 49 binary patterns, and three sets of 3D nano-printing images, totaling 25 unique visuals. These results present the largest number of recorded images with ultra-high resolution to date. Our innovative Pollen technique is expected to benefit the development of modern optical applications, including but not limited to optical encryption, optical data storage, lightweight display, and augmented reality and virtual reality. △ Less

Submitted 4 March, 2024; originally announced March 2024.

Comments: 12 pages, 5 figures

Proton-CAT: a Novel Strategy for Enhanced Proton Therapy

Authors: Zhao Sun, Zhencen He, Zhuohang He, Junxiang Wu, Liyuan Deng, Zhuohang He, Ziqi Chen, Junkang Jiang, Hang Zhu, Shuyu Zhang, Zhimin Hu

Abstract: We present a nitrogen-targeting-Proton-Carbon-Alpha-Therapy method, abbreviated as Proton-CAT, which partially converts protons into carbon-12 and $α$ particles through nuclear reactions between protons and nitrogen-15. Monte Carlo simulations validated the effectiveness of the Proton-CAT, and the study specifically focused on the distribution of relative energy deposition. The results indicated t… ▽ More We present a nitrogen-targeting-Proton-Carbon-Alpha-Therapy method, abbreviated as Proton-CAT, which partially converts protons into carbon-12 and $α$ particles through nuclear reactions between protons and nitrogen-15. Monte Carlo simulations validated the effectiveness of the Proton-CAT, and the study specifically focused on the distribution of relative energy deposition. The results indicated that the presence of nitrogen-15 enhanced the maximum dose level of protons, resulting in more effective damage confined to tumor cells. Statistical analysis of secondary ions has shown that the Proton-CAT significantly increases the production efficiencies of carbon-12 and $α$ particles. Furthermore, it has been revealed that elevating the nitrogen-15 concentration significantly boosts the dose of carbon and $α$ particles within the tumor region. The present work would contribute to the future development of proton therapy. △ Less

Submitted 16 April, 2024; v1 submitted 5 February, 2024; originally announced February 2024.

Comments: 5 pages, 4figures

Effect of the ${\rm^{15}N(p,α)^{12}C}$ reaction on the kinetic energy release of water molecule fragmentation

Authors: Zhuohang He, Zhencen He, Mingliang Duan, Junxiang Wu, Liyuan Deng, Ziqi Chen, Shuyu Zhang, Zhimin Hu

Abstract: In this work, we investigated the effect of ${\rm^{15}N(p,α)^{12}C}$ reaction produced by the collision between proton and ammonia monohydrate on the kinetic energy release (KER) of water molecule fragmentation. After the occurrence of the nuclear reaction, it was found that the charge states $q$ and the flight speeds $v$ are the main factors affecting the KER of water molecule fragmentation. With… ▽ More In this work, we investigated the effect of ${\rm^{15}N(p,α)^{12}C}$ reaction produced by the collision between proton and ammonia monohydrate on the kinetic energy release (KER) of water molecule fragmentation. After the occurrence of the nuclear reaction, it was found that the charge states $q$ and the flight speeds $v$ are the main factors affecting the KER of water molecule fragmentation. With the value of $q/v$ increases, the KER distribution gets wider and the peak position changes more pronounced. The energy gained by each fragment is related to the mass of the fragment and the distance of the fragment from the nuclear reaction. In this study, the fragments with smaller masses and the distances far away from the nuclear reaction get higher energies. The fragments of water molecules getting higher energy may induce other factors affecting the radiotherapy effect, which needs more detailed investigations in the future. △ Less

Submitted 1 February, 2024; v1 submitted 27 January, 2024; originally announced January 2024.

One-way multiple beam splitter designed by quantum-like shortcut-to-adiabatic passage

Authors: Jiahui Zhang, Yating Wei, Li Deng, Yueping Niu, Shangqing Gong

Abstract: Based on the quantum mechanical "Shortcut-to-Adiabatic passage" (STAP), a novel design for the efficient and robust multiple beam splitter is presented in this paper. This multiple beam splitter consists of one input and $N$ output waveguide channels, which are connected via a mediator waveguide (WG). To implement "STAP" but without additional couplings, this $(N+2)$-WG system is first reduced to… ▽ More Based on the quantum mechanical "Shortcut-to-Adiabatic passage" (STAP), a novel design for the efficient and robust multiple beam splitter is presented in this paper. This multiple beam splitter consists of one input and $N$ output waveguide channels, which are connected via a mediator waveguide (WG). To implement "STAP" but without additional couplings, this $(N+2)$-WG system is first reduced to a controllable $3$-WGs counterpart by "Morris-Shore" (MS) transformation. Consequently, the reduced system can be directly compatible with all possible "STAP" methods. The results show that this novel design can achieve arbitrary ratio of multiple beam splitting and can significantly shorten the length of the device, which expands the application of "STAP" in classical system and provides a direct visualization in space of typical ultra-fast phenomena in time. More uniquely, this new design exhibits a one-way energy transport behavior. These may have profound impacts on exploring quantum technologies for promoting advanced optical devices. △ Less

Submitted 27 October, 2024; v1 submitted 10 November, 2023; originally announced November 2023.

Erbium-ytterbium co-doped lithium niobate single-mode microdisk laser with an ultralow threshold of 1 uW

Authors: Minghui Li, Renhong Gao, Chuntao Li, Jianglin Guan, Haisu Zhang, Jintian Lin, Guanghui Zhao, Qian Qiao, Min Wang, Lingling Qiao, Li Deng, Ya Cheng

Abstract: We demonstrate single-mode microdisk lasers in the telecom band with ultra-low thresholds on erbium-ytterbium co-doped thin-film lithium niobate (TFLN). The active microdisk were fabricated with high-Q factors by photo-lithography assisted chemo-mechanical etching. Thanks to the erbium-ytterbium co-doping providing high optical gain, the ultra-low loss nanostructuring, and the excitation of high-Q… ▽ More We demonstrate single-mode microdisk lasers in the telecom band with ultra-low thresholds on erbium-ytterbium co-doped thin-film lithium niobate (TFLN). The active microdisk were fabricated with high-Q factors by photo-lithography assisted chemo-mechanical etching. Thanks to the erbium-ytterbium co-doping providing high optical gain, the ultra-low loss nanostructuring, and the excitation of high-Q coherent polygon modes which suppresses multi-mode lasing and allows high spatial mode overlap factor between pump and lasing modes, single-mode laser emission operating at 1530 nm wavelength was observed with an ultra-low threshold, under 980-nm-band optical pump. The threshold was measured as low as 1 uW, which is one order of magnitude smaller than the best results previously reported in single-mode active TFLN microlasers. And the conversion efficiency reaches 0.406%, which is also the highest value reported in single-mode active TFLN microlasers. △ Less

Submitted 19 September, 2023; originally announced September 2023.

Comments: 5 pages,3 figures

A flexible and accurate total variation and cascaded denoisers-based image reconstruction algorithm for hyperspectrally compressed ultrafast photography

Authors: Zihan Guo, Jiali Yao, Dalong Qi, Pengpeng Ding, Chengzhi Jin, Ning Xu, Zhiling Zhang, Yunhua Yao, Lianzhong Deng, Zhiyong Wang, Zhenrong Sun, Shian Zhang

Abstract: Hyperspectrally compressed ultrafast photography (HCUP) based on compressed sensing and the time- and spectrum-to-space mappings can simultaneously realize the temporal and spectral imaging of non-repeatable or difficult-to-repeat transient events passively in a single exposure. It possesses an incredibly high frame rate of tens of trillions of frames per second and a sequence depth of several hun… ▽ More Hyperspectrally compressed ultrafast photography (HCUP) based on compressed sensing and the time- and spectrum-to-space mappings can simultaneously realize the temporal and spectral imaging of non-repeatable or difficult-to-repeat transient events passively in a single exposure. It possesses an incredibly high frame rate of tens of trillions of frames per second and a sequence depth of several hundred, and plays a revolutionary role in single-shot ultrafast optical imaging. However, due to the ultra-high data compression ratio induced by the extremely large sequence depth as well as the limited fidelities of traditional reconstruction algorithms over the reconstruction process, HCUP suffers from a poor image reconstruction quality and fails to capture fine structures in complex transient scenes. To overcome these restrictions, we propose a flexible image reconstruction algorithm based on the total variation (TV) and cascaded denoisers (CD) for HCUP, named the TV-CD algorithm. It applies the TV denoising model cascaded with several advanced deep learning-based denoising models in the iterative plug-and-play alternating direction method of multipliers framework, which can preserve the image smoothness while utilizing the deep denoising networks to obtain more priori, and thus solving the common sparsity representation problem in local similarity and motion compensation. Both simulation and experimental results show that the proposed TV-CD algorithm can effectively improve the image reconstruction accuracy and quality of HCUP, and further promote the practical applications of HCUP in capturing high-dimensional complex physical, chemical and biological ultrafast optical scenes. △ Less

Submitted 6 September, 2023; originally announced September 2023.

Comments: 25 pages, 5 figures and 1 table

Ultra-high Q lithium niobate microring monolithically fabricated by photolithography assisted chemo-mechanical etching

Authors: Chuntao Li, Jianglin Guan, Jintian Lin, Renhong Gao, Min Wang, Lingling Qiao, Li Deng, Ya Cheng

Abstract: Thin-film lithium niobate (TFLN) has been considered as one of the most important platforms for constructing high-performance photonic integrated devices such as electro-optic modulators, frequency combs, classical/quantum light sources, and large-scale photonic integrated circuits, benefiting from its excellent optical properties of TFLN. The fabrication quality of TFLN photonic integrated device… ▽ More Thin-film lithium niobate (TFLN) has been considered as one of the most important platforms for constructing high-performance photonic integrated devices such as electro-optic modulators, frequency combs, classical/quantum light sources, and large-scale photonic integrated circuits, benefiting from its excellent optical properties of TFLN. The fabrication quality of TFLN photonic integrated devices plays an important role in the performance and the integration scale of these devices. As one of the element photonic structures, the state-of-the-art TFLN microrings reach an intrinsic Q factor higher than 10^7 with ultra-smooth sidewalls, fabricated by photolithography assisted chemo-mechanical etching (PLACE). However, it is isolated on the chip surface and a tapered fiber is required to couple the light into and out of the resonator. Furthermore, it is difficult to maintain such high-Q factors when the microrings are monolithically integrated with bus waveguides by PLACE, resulted from large coupling loss with biggish coupling gap. Here, a relatively narrow gap of an ultra-high Q microring monolithically integrated with the bus-waveguide is achieved with 3.8 um by optimizing PLACE process, and a high temperature annealing is carried out to improve the loaded (intrinsic) Q factor with 4.29 X 10^6 (4.04 X 10^7), leading an ultra-low propagation loss of less than 1 dB/m, which is approximately 3 times better than the best values previously reported in ion-slicing TFLN platform. △ Less

Submitted 18 June, 2023; originally announced June 2023.

Comments: 6 pages,3 figures,1 table

Evidence of a hydrated mineral enriched in water and ammonium molecules in the Chang'e-5 lunar sample

Authors: Shifeng Jin, Munan Hao, Zhongnan Guo, Bohao Yin, Yuxin Ma, Lijun Deng, Xu Chen, Yanpeng Song, Cheng Cao, Congcong Chai, Yunqi Ma, Jiangang Guo, Xiaolong Chen

Abstract: The presence and distribution of water on the Moon are fundamental to our understanding of the Earth-Moon system. Despite extensive research and remote detection, the origin and chemical form of lunar water (H2O) have remained elusive. In this study, we present the discovery of a hydrated mineral, (NH4)MgCl3*6H2O, in lunar soil samples returned by the Chang'e-5 mission, containing approximately 41… ▽ More The presence and distribution of water on the Moon are fundamental to our understanding of the Earth-Moon system. Despite extensive research and remote detection, the origin and chemical form of lunar water (H2O) have remained elusive. In this study, we present the discovery of a hydrated mineral, (NH4)MgCl3*6H2O, in lunar soil samples returned by the Chang'e-5 mission, containing approximately 41 wt% H2O. The mineral's structure and composition closely resemble novograblenovite, a terrestrial fumarole mineral formed through the reaction of hot basalt with water-rich volcanic gases, and carnallite, an earth evaporite mineral. We rule out terrestrial contamination or rocket exhaust as the origin of this hydrate, based on its chemical and isotopic compositions and formation conditions. The presence of ammonium indicates a more complex lunar degassing history and highlights its potential as a resource for lunar habitation. Our findings also suggest that water molecules can persist in sunlit areas of the Moon as hydrated salt, providing crucial constraints to the fugacity of water and ammonia vapor in lunar volcanic gases. △ Less

Submitted 28 June, 2024; v1 submitted 9 May, 2023; originally announced May 2023.

Comments: 28 pages, 4 figures

Realization of a quadrupole topological insulator phase in a gyromagnetic photonic crystal

Authors: Peiheng Zhou, Gui-Geng Liu, Zihao Wang, Yuan-Hang Hu, Shuwei Li, Qindong Xie, Yunpeng Zhang, Xiang Xi, Zhen Gao, Longjiang Deng, Baile Zhang

Abstract: The field of topological photonics was initiated with the realization of a Chern insulator phase in a gyromagnetic photonic crystal (PhC) with broken time-reversal symmetry (T), hosting chiral edge states that are topologically protected propagating modes. Recent advances in higher-order band topology have discovered another type of topological state, as manifested by those modes localized at the… ▽ More The field of topological photonics was initiated with the realization of a Chern insulator phase in a gyromagnetic photonic crystal (PhC) with broken time-reversal symmetry (T), hosting chiral edge states that are topologically protected propagating modes. Recent advances in higher-order band topology have discovered another type of topological state, as manifested by those modes localized at the corners of a sample, which are known as corner states. Here we report the realization of a quadrupole higher-order topological insulator phase in a gyromagnetic PhC, induced by a topological phase transition from the previously demonstrated Chern insulator phase. The evolution of the boundary modes from propagating chiral edge states to localized corner states has been characterized by microwave measurements. We also demonstrate topological bound states in the continuum, when the gyromagnetic PhC is magnetically tuned. These results extend the quadrupole topological insulator phase into T-broken systems, and integrate topologically protected propagating and localized modes in the same platform. △ Less

Submitted 6 February, 2023; originally announced February 2023.

Comments: 7 pages,4 figures

Single-shot polarization-resolved ultrafast mapping photography

Authors: Pengpeng Ding, Dalong Qi, Yunhua Yao, Yilin He, Jiali Yao, Chengzhi Jin, Zihan Guo, Lianzhong Deng, Zhenrong Sun, Shian Zhang

Abstract: Single-shot ultrafast optical imaging plays a very important role in the detection of transient scenes, especially in capturing irreversible or stochastic dynamic scenes. To break the limit of time response speed of electronic devices, such as charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) detectors, ultrafast optical imaging techniques usually convert the time infor… ▽ More Single-shot ultrafast optical imaging plays a very important role in the detection of transient scenes, especially in capturing irreversible or stochastic dynamic scenes. To break the limit of time response speed of electronic devices, such as charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) detectors, ultrafast optical imaging techniques usually convert the time information of a transient scene into the wavelength, angle, space or spatial frequency of the illumination light in previous studies. In this work, we propose a novel polarization-resolved ultrafast mapping photography (PUMP) technique by converting the time information into the polarization. Here, the spatiotemporal information of a dynamic scene is loaded into a rotationally polarized illumination laser pulse, and a polarization filtering in imaging detection and a deconvolution algorithm in image reconstruction are used to extract the original dynamic scene. In our PUMP system, the temporal resolution is 850 fs, the spatial resolution is 28.5 lp/mm at 700 micrometer by 700 micrometer field of view, and the number of frames is 16. By using PUMP, a spatiotemporal dynamics of femtosecond laser ablation in an indium tin oxide film on glass substrate is successfully captured. PUMP provides a new solution for measuring the transient scenes in a snapshot, which will bring a very wide range of applications in the field of ultrafast science. △ Less

Submitted 4 February, 2023; originally announced February 2023.

Monolithically integrated high-power narrow-bandwidth microdisk laser

Authors: Jianglin Guan, Chuntao Li, Renhong Gao, Haisu Zhang, Jiantian Lin, Minghui Li, Min Wang, Lingling Qiao, Li Deng, Ya Cheng

Abstract: Integrated on-chip microdisk lasers have attracted great attention as a light source of compact size, low lasing threshold and narrow bandwidth. However, challenges remain unresolved in terms of single mode operation at high output power while maintaining the ultra-narrow bandwidth. In this work, we demonstrate monolithically integrated on-chip single-frequency microdisk lasers coupled with bus-wa… ▽ More Integrated on-chip microdisk lasers have attracted great attention as a light source of compact size, low lasing threshold and narrow bandwidth. However, challenges remain unresolved in terms of single mode operation at high output power while maintaining the ultra-narrow bandwidth. In this work, we demonstrate monolithically integrated on-chip single-frequency microdisk lasers coupled with bus-waveguides fabricated by photolithography assisted chemo-mechanical etching. Owing to the high-Q factor of a polygon whispering gallery mode formed in the microdisk and long cavity lengths (e.g., 409 um and 1 mm), a microdisk laser with a narrow linewidth of 0.11 MHz and a maximum output power of 62.1 uW has been achieved at room temperature. △ Less

Submitted 22 December, 2022; v1 submitted 21 December, 2022; originally announced December 2022.

Comments: 6 pages,5 figures

Solar Ring Mission: Building a Panorama of the Sun and Inner-heliosphere

Authors: Yuming Wang, Xianyong Bai, Changyong Chen, Linjie Chen, Xin Cheng, Lei Deng, Linhua Deng, Yuanyong Deng, Li Feng, Tingyu Gou, Jingnan Guo, Yang Guo, Xinjun Hao, Jiansen He, Junfeng Hou, Huang Jiangjiang, Zhenghua Huang, Haisheng Ji, Chaowei Jiang, Jie Jiang, Chunlan Jin, Xiaolei Li, Yiren Li, Jiajia Liu, Kai Liu , et al. (29 additional authors not shown)

Abstract: Solar Ring (SOR) is a proposed space science mission to monitor and study the Sun and inner heliosphere from a full 360° perspective in the ecliptic plane. It will deploy three 120°-separated spacecraft on the 1-AU orbit. The first spacecraft, S1, locates 30° upstream of the Earth, the second, S2, 90° downstream, and the third, S3, completes the configuration. This design with necessary science in… ▽ More Solar Ring (SOR) is a proposed space science mission to monitor and study the Sun and inner heliosphere from a full 360° perspective in the ecliptic plane. It will deploy three 120°-separated spacecraft on the 1-AU orbit. The first spacecraft, S1, locates 30° upstream of the Earth, the second, S2, 90° downstream, and the third, S3, completes the configuration. This design with necessary science instruments, e.g., the Doppler-velocity and vector magnetic field imager, wide-angle coronagraph, and in-situ instruments, will allow us to establish many unprecedented capabilities: (1) provide simultaneous Doppler-velocity observations of the whole solar surface to understand the deep interior, (2) provide vector magnetograms of the whole photosphere - the inner boundary of the solar atmosphere and heliosphere, (3) provide the information of the whole lifetime evolution of solar featured structures, and (4) provide the whole view of solar transients and space weather in the inner heliosphere. With these capabilities, Solar Ring mission aims to address outstanding questions about the origin of solar cycle, the origin of solar eruptions and the origin of extreme space weather events. The successful accomplishment of the mission will construct a panorama of the Sun and inner-heliosphere, and therefore advance our understanding of the star and the space environment that holds our life. △ Less

Submitted 23 October, 2022; v1 submitted 19 October, 2022; originally announced October 2022.

Comments: 41 pages, 6 figures, 1 table, to be published in Advances in Space Research

Theory and Experiments of Pressure-Tunable Broadband Light Emission from Self-Trapped Excitons in Metal Halide Crystals

Authors: Shenyu Dai, Xinxin Xing, Viktor G. Hadjiev, Zhaojun Qin, Tian Tong, Guang Yang, Chong Wang, Lijuan Hou, Liangzi Deng, Zhiming Wang, Guoying Feng, Jiming Bao

Abstract: Hydrostatic pressure has been commonly applied to tune broadband light emissions from self-trapped excitons (STE) in perovskites for producing white light and study of basic electron-phonon interactions. However, a general theory is still lacking to understand pressure-driven evolution of STE emissions. In this work we first identify a theoretical model that predicts the effect of hydrostatic pres… ▽ More Hydrostatic pressure has been commonly applied to tune broadband light emissions from self-trapped excitons (STE) in perovskites for producing white light and study of basic electron-phonon interactions. However, a general theory is still lacking to understand pressure-driven evolution of STE emissions. In this work we first identify a theoretical model that predicts the effect of hydrostatic pressure on STE emission spectrum, we then report the observation of extremely broadband photoluminescence emission and its wide pressure spectral tuning in 2D indirect bandgap CsPb2Br5 crystals. An excellent agreement is found between the theory and experiment on the peculiar experimental observation of STE emission with a nearly constant spectral bandwidth but linearly increasing energy with pressure below 2 GPa. Further analysis by the theory and experiment under higher pressure reveals that two types of STE are involved and respond differently to external pressure. We subsequently survey published STE emissions and discovered that most of them show a spectral blue-shift under pressure, as predicted by the theory. The identification of an appropriate theoretical model and its application to STE emission through the coordinate configuration diagram paves the way for engineering the STE emission and basic understanding of electron-phonon interaction. △ Less

Submitted 23 September, 2022; originally announced September 2022.

Journal ref: Materials Today Physics 30 (2023): 100926

Epitaxial growth of high quality $Mn_3Sn$ thin films by pulsed laser deposition

Authors: Dong Gao, Zheng Peng, Ningbin Zhang, Yunfei Xie, Yucong Yang, Weihao Yang, Shuang Xia, Wei Yan, Longjiang Deng, Tao Liu, Jun Qin, Xiaoyan Zhong, Lei Bi

Abstract: Non-collinear antiferromagnet Weyl semimetal $Mn_3Sn$ have attracted great research interest recently. Although large anomalous Hall effect, anomalous Nernst effect and magneto-optical effect have been observed in $Mn_3Sn$, most studies are based on single crystals. So far, it is still challenging to grow high quality epitaxial $Mn_3Sn$ thin films with transport and optical properties comparable t… ▽ More Non-collinear antiferromagnet Weyl semimetal $Mn_3Sn$ have attracted great research interest recently. Although large anomalous Hall effect, anomalous Nernst effect and magneto-optical effect have been observed in $Mn_3Sn$, most studies are based on single crystals. So far, it is still challenging to grow high quality epitaxial $Mn_3Sn$ thin films with transport and optical properties comparable to their single crystal counterparts. Here, we report the structure, magneto-optical and transport properties of epitaxial $Mn_3Sn$ thin films fabricated by pulsed laser deposition (PLD). Highly oriented $Mn_{3+x}Sn_{1-x}$ (0001) and (11$\bar2$0) epitaxial films are successfully growth on single crystalline $Al_2O_3$ and MgO substrates. Large anomalous Hall effect (AHE) up to $\left| ΔR_H\right|$=3.02 $μΩ\cdot cm$, and longitudinal magneto-optical Kerr effect (LMOKE) with $θ_K$ = 38.1 mdeg at 633 nm wavelength are measured at 300 K temperature, which are comparable to $Mn_3Sn$ single crystals. Our work demonstrates that high quality $Mn_3Sn$ epitaxial thin films can be fabricated by PLD, paving the way for future device applications. △ Less

Submitted 8 August, 2022; originally announced August 2022.

Magnetically tunable zero-index metamaterials

Authors: Yucong Yang, Yueyang Liu, Jun Qin, Songgang Cai, Jiejun Su, Peiheng Zhou, Longjiang Deng, Yang Li, Lei Bi

Abstract: Zero-index metamaterials (ZIMs) feature a uniform electromagnetic mode over a large area in arbitrary shapes, enabling many applications including high-transmission supercouplers with arbitrary shapes, direction-independent phase matching for nonlinear optics, and collective emission of many quantum emitters. However, most ZIMs reported till date are passive, with no method for the dynamic modulat… ▽ More Zero-index metamaterials (ZIMs) feature a uniform electromagnetic mode over a large area in arbitrary shapes, enabling many applications including high-transmission supercouplers with arbitrary shapes, direction-independent phase matching for nonlinear optics, and collective emission of many quantum emitters. However, most ZIMs reported till date are passive, with no method for the dynamic modulation of their electromagnetic properties. Here, we design and fabricate a magnetically tunable ZIM consisting of yttrium iron garnet (YIG) pillars sandwiched between two copper clad laminates in the microwave regime. By harnessing the Cotton-Mouton effect of YIG, the metamaterial was successfully toggled between gapless and bandgap states, leading to a "phase transition" between a zero-index phase and a single negative phase of the metamaterial. Using an S-shaped ZIM supercoupler, we experimentally demonstrated a tunable supercoupling state with a low intrinsic loss of 0.95 dB and a high extinction ratio of up to 30.63 dB at 9 GHz. Our work enables dynamic modulation of the electromagnetic characteristics of ZIMs, enabling various applications in tunable linear, nonlinear, quantum and nonreciprocal electromagnetic devices. △ Less

Submitted 8 June, 2022; originally announced June 2022.

The Temporal and Spatial Behaviors of CME Occurrence Rate at Different Latitudes

Authors: Jiaqi Lin, Feng Wang, Linhua Deng, Hui Deng, Ying Mei, Yangfan Xie

Abstract: The statistical study of the Coronal Mass Ejections (CMEs) is a hot topic in solar physics. To further reveal the temporal and spatial behaviors of the CMEs at different latitudes and heights, we analyzed the correlation and phase relationships between the occurrence rate of CMEs, the Coronal Brightness Index (CBI), and the 10.7-cm solar radio flux (F10.7). We found that the occurrence rate of the… ▽ More The statistical study of the Coronal Mass Ejections (CMEs) is a hot topic in solar physics. To further reveal the temporal and spatial behaviors of the CMEs at different latitudes and heights, we analyzed the correlation and phase relationships between the occurrence rate of CMEs, the Coronal Brightness Index (CBI), and the 10.7-cm solar radio flux (F10.7). We found that the occurrence rate of the CMEs correlates with CBI relatively stronger at high latitudes (>=60) than at low latitudes (<=50). At low latitudes, the occurrence rate of the CMEs correlates relatively weaker with CBI than F10.7. There is a relatively stronger correlation relationship between CMEs, F10.7, and CBI during Solar Cycle 24(SC24) than Solar Cycle 23 (SC23). During SC23, the high-latitude CME occurrence rate lags behind F10.7 by three months, and during SC24, the low-latitude CME occurrence rate leads to the low-latitude CBI by one month. The correlation coefficient values turn out to be larger when the very faint CMEsare removed from the samples of the CDAW catalog. Based on our results, we may speculate that the source regions of the high/low-latitude CMEs may vary in height, and the process of magnetic energy accumulation and dissipation is from the lower to the upper atmosphere of the Sun. The temporal offsets between different indicators could help us better understand the physical processes responsible for the solar-terrestrial interactions. △ Less

Submitted 12 May, 2022; originally announced May 2022.

Comments: 11 pages, 7 figures, 2 tables. Accepted by APJ

Magnet-free nonreciprocal metasurface for on-demand bi-directional phase modulation

Authors: Weihao Yang, Jun Qin, Jiawei Long, Wei Yan, Yucong Yang, Chaoyang Li, En Li, Juejun Hu, Longjiang Deng, Qingyang Du, Lei Bi

Abstract: Unconstrained by Lorentz reciprocity, nonreciprocal metasurfaces are uniquely capable of encoding distinctive optical functions on forward- and backward-propagating waves. The nonreciprocal metasurfaces reported to date require external electric or magnetic field biasing or rely on nonlinear effects, both of which are challenging to practically implement. Here, we propose and experimentally realiz… ▽ More Unconstrained by Lorentz reciprocity, nonreciprocal metasurfaces are uniquely capable of encoding distinctive optical functions on forward- and backward-propagating waves. The nonreciprocal metasurfaces reported to date require external electric or magnetic field biasing or rely on nonlinear effects, both of which are challenging to practically implement. Here, we propose and experimentally realize a magnet-free, linear, and passive nonreciprocal metasurface based on self-biased magnetic meta-atoms. Record transmittance up to 77% and operation angle reaching 64 degree are experimentally demonstrated. Moreover, on-demand bidirectional phase modulation in a "LEGO-like" manner is theoretically proposed and experimentally demonstrated, enabling a cohort of nonreciprocal functionalities such as microwave isolation, nonreciprocal beam steering, nonreciprocal focusing, and nonreciprocal holography. The design can also be extended to MHz and optical frequencies, taking advantage of the wide variety of self-biased gyrotropic materials available. We foresee that the nonreciprocal metasurfaces demonstrated in this work will have a significant practical impact for applications ranging from nonreciprocal antennas and radomes to full-duplex wireless communication and radar systems. △ Less

Submitted 6 April, 2022; originally announced April 2022.

Comments: 18 pages, 5 figures

High Noise Immune Time-domain Inversion via Cascade Network (TICaN) for Complex Scatterers

Authors: Hongyu Gao, Yinpeng Wang, Qiang Ren, Zixi Wang, Liangcheng Deng, Chenyu Shi

Abstract: In this paper, a high noise immune time-domain inversion cascade network (TICaN) is proposed to reconstruct scatterers from the measured electromagnetic fields. The TICaN is comprised of a denoising block aiming at improving the signal-to-noise ratio, and an inversion block to reconstruct the electromagnetic properties from the raw time-domain measurements. The scatterers investigated in this stud… ▽ More In this paper, a high noise immune time-domain inversion cascade network (TICaN) is proposed to reconstruct scatterers from the measured electromagnetic fields. The TICaN is comprised of a denoising block aiming at improving the signal-to-noise ratio, and an inversion block to reconstruct the electromagnetic properties from the raw time-domain measurements. The scatterers investigated in this study include complicated geometry shapes and high contrast, which cover the stratum layer, lossy medium and hyperfine structure, etc. After being well trained, the performance of the TICaN is evaluated from the perspective of accuracy, noise-immunity, computational acceleration, and generalizability. It can be proven that the proposed framework can realize high-precision inversion under high-intensity noise environments. Compared with traditional reconstruction methods, TICaN avoids the tedious iterative calculation by utilizing the parallel computing ability of GPU and thus significantly reduce the computing time. Besides, the proposed TICaN has certain generalization ability in reconstructing the unknown scatterers such as the famous Austria rings. Herein, it is confident that the proposed TICaN will serve as a new path for real-time quantitative microwave imaging for various practical scenarios. △ Less

Submitted 2 March, 2022; originally announced March 2022.

Comments: 9 pages, 11 figures

Frequency stabilization of a 739 nm laser to an $I_2$ spectrum for trapped Ytterbium ions

Authors: Hao Wu, PengFei Lu, Yang Liu, JiangYong Hu, QiFeng Lao, XinXin Rao, LunHua Deng, Feng Zhu, Le Luo

Abstract: We report on the frequency stabilization of a 739 nm Ti:sapphire laser to a hyperfine component of the $^{127}I_{2}$ B(1)-X(11) P(70) transition using acousto-optic modulation transfer spectroscopy (MTS). A frequency stability of $3.83\times 10^{-11}$ around 13 s averaging time is achieved when the laser frequency is stabilized. The observed hyperfine transition of the molecular iodine is an ideal… ▽ More We report on the frequency stabilization of a 739 nm Ti:sapphire laser to a hyperfine component of the $^{127}I_{2}$ B(1)-X(11) P(70) transition using acousto-optic modulation transfer spectroscopy (MTS). A frequency stability of $3.83\times 10^{-11}$ around 13 s averaging time is achieved when the laser frequency is stabilized. The observed hyperfine transition of the molecular iodine is an ideal frequency reference for locking the lasers used in experiments with trapped ytterbium ions, since its second harmonic frequency is the $^{2}S_{\frac{1}{2}}-^{2}P_{\frac{1}{2}}$ transition of the ytterbium ion at 369.5 nm. By investigating the line broadening effects due to the iodine vapor pressure and laser power, the locking is optimized to the theoretical signal to noise ratio (TSNR) of this iodine transition. △ Less

Submitted 2 March, 2022; originally announced March 2022.

Journal ref: JOSA B 39.5 (2022)

Colliding-probe bi-atomic magnetometers via energy circulation: Breaking symmetry-enforced magneto-optical rotation blockade

Authors: Lu Deng

Abstract: We have developed an inelastic wave scattering based colliding-probe bi-atomic magnetometer theory. We show a propagation growth blockade in single probe based magnetic field sensing schemes, revealing the root cause of strong suppression of nonlinear magneto-optical rotation effect (NMORE) in single probe based atomic magnetometers. We further show, both experimentally and theoretically, a collid… ▽ More We have developed an inelastic wave scattering based colliding-probe bi-atomic magnetometer theory. We show a propagation growth blockade in single probe based magnetic field sensing schemes, revealing the root cause of strong suppression of nonlinear magneto-optical rotation effect (NMORE) in single probe based atomic magnetometers. We further show, both experimentally and theoretically, a colliding probe bi-atomic magnetometer that lifts this NMORE blockade. The directional energy circulation in this new atomic magnetometry technique results in more than two orders of magnitude increase in NMORE signal as well as greater than 6dB increase of magnetic field detection sensitivity. The new technique may have broad applications in photon gates and switching operations. △ Less

Submitted 13 March, 2022; v1 submitted 25 February, 2022; originally announced March 2022.

Comments: Revised Fig.4 with the same color code for Figs. 4(a) and 4(b). Simplified Eqs. (11a) and (11b)

Decoupled phase modulation for circularly polarized lights via chiral metasurface

Authors: Renchao Jin, Lin Deng, Lili Tang, Yue Cao, Yongmin Liu, Zheng-Gao Dong

Abstract: Metasurfaces are believed as one of the best candidates in nano-optical devices, attributed to the key feasible modulation features of phase, polarization, and local field enhancement by structural designing. However, current methods of propagation- and geometric-phase modulation are interrelated between two eigen spin-states. This means that when the left-handed component phase of a beam is modul… ▽ More Metasurfaces are believed as one of the best candidates in nano-optical devices, attributed to the key feasible modulation features of phase, polarization, and local field enhancement by structural designing. However, current methods of propagation- and geometric-phase modulation are interrelated between two eigen spin-states. This means that when the left-handed component phase of a beam is modulated by metasurfaces, its right-handed component phase will change accordingly, which limits the versatility of spin-decoupled applications. In this paper, we experimentally and numerically demonstrate a new phase modulation pathway based on chiral V-shaped holes, which enable fully decoupled one-handed phase modulation of the two eigen spin-states. Two enantiomers are proposed to realize decoupled functions for the two eign-states, e.g., the enantiomer can manipulate the left-handed component phase of a laser beam without changes of the right-handed component. This proposed method has significant meaning in metasurfaces, which can expand the methods of phase engineering. △ Less

Submitted 21 February, 2022; originally announced February 2022.

Observation of optical gyromagnetic properties in a magneto-plasmonic metamaterial

Authors: Weihao Yang, Qing Liu, Hanbin Wang, Yiqin Chen, Run Yang, Shuang Xia, Yi Luo, Longjiang Deng, Jun Qin, Huigao Duan, Lei Bi

Abstract: Metamaterials with artificial optical properties have attracted significant research interest. In particular, artificial magnetic resonances in non-unity permeability tensor at optical frequencies in metamaterials have been reported. However, only non-unity diagonal elements of the permeability tensor have been demonstrated to date. A gyromagnetic permeability tensor with non-zero off-diagonal ele… ▽ More Metamaterials with artificial optical properties have attracted significant research interest. In particular, artificial magnetic resonances in non-unity permeability tensor at optical frequencies in metamaterials have been reported. However, only non-unity diagonal elements of the permeability tensor have been demonstrated to date. A gyromagnetic permeability tensor with non-zero off-diagonal elements has not been observed at the optical frequencies. Here we report the observation of gyromagnetic properties in the near-infrared wavelength range in a magneto-plasmonic metamaterial. The non-zero off-diagonal permeability tensor element causes the transverse magneto-optical Kerr effect (TMOKE) under s-polarized incidence that otherwise vanishes if the permeability tensor is not gyromagnetic. By retrieving the permeability tensor elements from reflection, transmission, and TMOKE spectra, we show that the effective off-diagonal permeability tensor elements reach the 10-3 level at the resonance wavelength (~900 nm) of the split-ring resonators that is at least two orders of magnitude higher than that of magneto-optical materials at the same wavelength. The artificial gyromagnetic permeability is attributed to the change in the local electric field direction modulated by the split-ring resonators. Our study demonstrates the possibility of engineering the permeability and permittivity tensors in metamaterials at arbitrary frequencies, thereby promising a variety of applications of next-generation nonreciprocal photonic devices, magneto-plasmonic sensors, and active metamaterials. △ Less

Submitted 11 October, 2021; originally announced October 2021.

Circular displacement current induced anomalous magneto-optical effects in high index Mie resonators

Authors: Shuang Xia, Daria Ignatyeva, Qing Liu, Hanbin Wang, Weihao Yang, Jun Qin, Yiqin Chen, Huigao Duan, Yi Luo, Ondrej Novak, Martin Veis, Longjiang Deng, Vladimir I. Belotelov, Lei Bi

Abstract: Dielectric Mie nanoresonators showing strong light-matter interaction at the nanoscale may enable new functionality in photonic devices. Recently, strong magneto-optical effects have been observed in magneto-optical nanophotonic devices due to the electromagnetic field localization. However, most reports so far have been focused on the enhancement of conventional magneto-optical effects. Here, we… ▽ More Dielectric Mie nanoresonators showing strong light-matter interaction at the nanoscale may enable new functionality in photonic devices. Recently, strong magneto-optical effects have been observed in magneto-optical nanophotonic devices due to the electromagnetic field localization. However, most reports so far have been focused on the enhancement of conventional magneto-optical effects. Here, we report the observation of circular displacement current induced anomalous magneto-optical effects in high-index-contrast Si/Ce:YIG/YIG/SiO2 Mie resonators. In particular, giant modulation of light intensity in transverse magnetic configuration up to 6.4 % under s-polarized incidence appears, which is non-existent in planar magneto-optical thin films. Apart from that, we observe a large rotation of transmitted light polarization in the longitudinal magnetic configuration under near normal incidence conditions, which is two orders of magnitude higher than for a planar magneto-optical thin film. These phenomena are essentially originated from the unique circular displacement current when exciting the magnetic resonance modes in the Mie resonators, which changes the incident electric field direction locally. Our work indicates an uncharted territory of light polarization control based on the complex modal profiles in all-dielectric magneto-optical Mie resonators and metasurfaces, which opens the door for versatile control of light propagation by magnetization for a variety of applications in vectoral magnetic field and biosensing, free space non-reciprocal photonic devices, magneto-optical imaging and optomagnetic memories. △ Less

Submitted 1 August, 2021; originally announced August 2021.

Single-photon non-reciprocity with an integrated magneto-optical isolator

Authors: Shang-Yu Ren, Wei Yan, Lan-Tian Feng, Yang Chen, Yun-Kun Wu, Xiao-Zhuo Qi, Xiao-JingLiu, Yu-Jie Cheng, Bo-Yu Xu, Long-Jiang Deng, Guang-Can Guo, Lei Bi, Xi-Feng Ren

Abstract: Non-reciprocal photonic devices are essential components of classical optical information processing. It is interesting and important to investigate their feasibility in the quantum world. In this work, the quantum properties of an on-chip silicon nitride (SiN)-based magneto-optical (MO) isolator were studied using a single-photon non-reciprocal dynamical transmission experiment. The measured isol… ▽ More Non-reciprocal photonic devices are essential components of classical optical information processing. It is interesting and important to investigate their feasibility in the quantum world. In this work, the quantum properties of an on-chip silicon nitride (SiN)-based magneto-optical (MO) isolator were studied using a single-photon non-reciprocal dynamical transmission experiment. The measured isolation ratio for single photons achieved was 12.33 dB, which proved the functionality of our on-chip isolator. The quantum coherence of the passing single photons was further verified using high-visibility quantum interference. Our work will promote on-chip isolators within the integrated quantum circuits and help introduce novel phenomena in quantum information processes. △ Less

Submitted 20 July, 2021; originally announced July 2021.

Comments: 5 pages, 4figures

Coherent mode-combined ultra-narrow-linewidth single-mode micro-disk laser

Authors: Jintian Lin, Saeed Farajollahi, Zhiwei Fang, Ni Yao, Renhong Gao, Jianglin Guan, Li Deng, Tao Lu, Min Wang, Haisu Zhang, Wei Fang, Lingling Qiao, Ya Cheng

Abstract: Integrated single-mode microlasers with ultra-narrow linewidths play a game-changing role in a broad spectrum of applications ranging from coherent communication and LIDAR to metrology and sensing. Generation of such light sources in a controllable and cost-effective manner remains an outstanding challenge due to the difficulties in the realization of ultra-high Q active micro-resonators with supp… ▽ More Integrated single-mode microlasers with ultra-narrow linewidths play a game-changing role in a broad spectrum of applications ranging from coherent communication and LIDAR to metrology and sensing. Generation of such light sources in a controllable and cost-effective manner remains an outstanding challenge due to the difficulties in the realization of ultra-high Q active micro-resonators with suppressed mode numbers. Here, we report a microlaser generated in an ultra-high Q Erbium doped lithium niobate (LN) micro-disk. Through the formation of coherently combined polygon modes at both pump and laser wavelengths, the microlaser exhibits single mode operation with an ultra-narrow-linewidth of 98 Hz. In combination with the superior electro-optic and nonlinear optical properties of LN crystal, the mass-producible on-chip single-mode microlaser will provide an essential building block for the photonic integrated circuits demanding high precision frequency control and reconfigurability. △ Less

Submitted 19 July, 2021; originally announced July 2021.

Lithium niobate microring with ultra-high Q factor above 10^8

Authors: Renhong Gao, Ni Yao, Jianglin Guan, Li Deng, Jintian Lin, Min Wang, Lingling Qiao, Wei Fang, Ya Cheng

Abstract: We demonstrate ultra-high Q factor microring resonators close to the intrinsic material absorption limit on lithium niobate on insulator. The microrings are fabricated on pristine lithium niobate (LN) thin film wafer thinned from LN bulk via chemo-mechanical etching without ion slicing and ion etching. A record-high Q factor up to times ten to the power of 8th at the wavelength of 1550 nm is achie… ▽ More We demonstrate ultra-high Q factor microring resonators close to the intrinsic material absorption limit on lithium niobate on insulator. The microrings are fabricated on pristine lithium niobate (LN) thin film wafer thinned from LN bulk via chemo-mechanical etching without ion slicing and ion etching. A record-high Q factor up to times ten to the power of 8th at the wavelength of 1550 nm is achieved because of the ultra-smooth interface of the microrings and the absence of ion induced lattice damage, indicating an ultra-low waveguide propagation loss of about 0.28 dB per meter. The ultra-high Q microrings will pave the way for integrated quantum light source, frequency comb generation, and nonlinear optical processes. △ Less

Submitted 28 June, 2021; originally announced June 2021.

Comments: 6 pages, 3 figures

On-chip ultra-narrow-linewidth single-mode microlaser on lithium niobate on insulator

Authors: Renhong Gao, Jianglin Guan, Ni Yao, Li Deng, Jintian Lin, Min Wang, Lingling Qiao, Zhenhua Wang, Youting Liang, Yuan Zhou, Ya Cheng

Abstract: We report an on-chip single mode microlaser with low-threshold fabricated on Erbium doped lithium niobate on insulator (LNOI). The single mode laser emission at 1550.5 nm wavelength is generated in a coupled photonic molecule, which is facilitated by Vernier effect when pumping the photonic molecule at 970 nm. A threshold pump power as low as 200 uW is demonstrated thanks to the high quality facto… ▽ More We report an on-chip single mode microlaser with low-threshold fabricated on Erbium doped lithium niobate on insulator (LNOI). The single mode laser emission at 1550.5 nm wavelength is generated in a coupled photonic molecule, which is facilitated by Vernier effect when pumping the photonic molecule at 970 nm. A threshold pump power as low as 200 uW is demonstrated thanks to the high quality factor above 10^6. Moreover, the linewidth of the microlaser reaches 4 kHz, which is the best result in LNOI microlasers. Such single mode micro-laser lithographically fabricated on chip is highly in demand by photonic community. △ Less

Submitted 29 April, 2021; v1 submitted 27 April, 2021; originally announced April 2021.

Broadband highly efficient nonlinear optical processes in on-chip integrated lithium niobate microdisk resonators of Q-factor above 10^8

Authors: Renhong Gao, Haisu Zhang, Fang Bo, Wei Fang, Zhenzhong Hao, Ni Yao, Jintian Lin, Jianglin Guan, Li Deng, Min Wang, Lingling Qiao, Ya Cheng

Abstract: We demonstrated broadband highly efficient optical nonlinear processes in on-chip integrated lithium niobate (LN) microdisk resonators. The Q factors of the micro-resonators fabricated by femtosecond laser writing and chemo-mechanical polishing are reliably above 10^8, approaching the intrinsic material absorption limit of LN. Broadband nonlinear processes, including optical parametric oscillation… ▽ More We demonstrated broadband highly efficient optical nonlinear processes in on-chip integrated lithium niobate (LN) microdisk resonators. The Q factors of the micro-resonators fabricated by femtosecond laser writing and chemo-mechanical polishing are reliably above 10^8, approaching the intrinsic material absorption limit of LN. Broadband nonlinear processes, including optical parametric oscillation (OPO), second harmonic generation (SHG), third harmonic generation, and fourth harmonic generation, were observed with ultrahigh efficiencies in the same LN microdisk without introducing domain inversion, thanks to the natural quasi phase-matching and the dense spectral modes of the X-cut LN microdisk with millimeter diameter. The threshold of OPO and the absolute conversion efficiency of SHG are 19.6 microwatt and 66%, both surpass the state-of-the-art values among on-chip LN micro-resonators demonstrated so far. The broadband and highly efficient nonlinear frequency conversions achieved with the ultrahigh-Q LN microdisk resonators promise high-density integration of nonlinear photonic devices such as frequency convertors and entangled photon sources. △ Less

Submitted 11 March, 2021; v1 submitted 31 January, 2021; originally announced February 2021.

Comments: 27 pages, 9 figures

Accelerating single-crystal growth by stimulated and self-guided channeling

Authors: Yan Ren, Changfeng Fang, Chengjie Zhu, Yvonne Y. Li, Bo Durbeej, Xian Zhao, Lu Deng

Abstract: We report a self-guided and "stimulated" single-crystal growth acceleration effect in static super-saturated aqueous solutions, producing inorganic (KH$_2$PO$_4$) and organic (tetraphenyl-phosphonium-family) nonlinear optical single-crystals with novel morphologies. The extraordinarily fast unidirectional growth in the presence of complete lateral growth suppression defies all current impurity, de… ▽ More We report a self-guided and "stimulated" single-crystal growth acceleration effect in static super-saturated aqueous solutions, producing inorganic (KH$_2$PO$_4$) and organic (tetraphenyl-phosphonium-family) nonlinear optical single-crystals with novel morphologies. The extraordinarily fast unidirectional growth in the presence of complete lateral growth suppression defies all current impurity, defect and dislocation based crystal growth inhibition mechanisms. We propose a self-channeling-stimulated accelerated growth theory that can satisfactorily explain all experimental results. Using molecular dynamics analysis and a modified two-component crystal growth model that includes microscopic surface molecular selectivity we show the lateral growth arrest is the combined result of the self-channeling and a self-shielding effect. These single-crystals exhibit remarkable mechanical flexibility in winding and twisting, demonstrating their unique advantages for chip-size quantum and biomedical applications, as well as for production of high-yield/high-potency pharmaceutical materials. △ Less

Submitted 27 January, 2021; originally announced January 2021.

Generation and Focusing of Orbital Angular Momentum Based on Polarized Reflectarray at Microwave Frequency

Authors: Fengxia Li, Haiyan Chen, Yang Zhou, Jian Wei You, Nicolae C. Panoiu, Peiheng Zhou, Longjiang Deng

Abstract: A novel polarized reflectarray is designed, fabricated, and experimentally characterized to show its flexibility and efficiency to control wave generation and focusing of orbital angular momentum (OAM) vortices with desirable OAM modes in the microwave frequency regime. In order to rigorously study the generation and focusing of OAM, a versatile analytical theory is proposed to theoretically study… ▽ More A novel polarized reflectarray is designed, fabricated, and experimentally characterized to show its flexibility and efficiency to control wave generation and focusing of orbital angular momentum (OAM) vortices with desirable OAM modes in the microwave frequency regime. In order to rigorously study the generation and focusing of OAM, a versatile analytical theory is proposed to theoretically study the compensation phase of reflectarray. Two prototypes of microwave reflectarrays are fabricated and experimentally characterized at 12 GHz, one for generation and one for focusing of OAM-carrying beams. Compared with the OAM-generating reflectarray, the reflectarray for focusing OAM vortex can significantly reduce the beam diameter, and this can further improve the transmission efficiency of the OAM vortex beams. We also show that the numerical and experimental results agree very well. The proposed design method and reflectarrays may spur the development of new efficient approaches to generate and focus OAM vortex waves for applications to microwave wireless communications. △ Less

Submitted 25 November, 2020; originally announced December 2020.

Comments: 10 pages, 10 figures

Waveguide integrated high performance magneto-optical isolators and circulators on silicon nitride platforms

Authors: Wei Yan, Yucong Yang, Shuyuan Liu, Yan Zhang, Shuang Xia, Tongtong Kang, Weihao Yang, Jun Qin, Longjiang Deng, Lei Bi

Abstract: Optical isolators and circulators are indispensable for photonic integrated circuits (PICs). Despite of significant progress in silicon-on-insulator (SOI) platforms, integrated optical isolators and circulators have been rarely reported on silicon nitride (SiN) platforms. In this paper, we report monolithic integration of magneto-optical (MO) isolators on SiN platforms with record high performance… ▽ More Optical isolators and circulators are indispensable for photonic integrated circuits (PICs). Despite of significant progress in silicon-on-insulator (SOI) platforms, integrated optical isolators and circulators have been rarely reported on silicon nitride (SiN) platforms. In this paper, we report monolithic integration of magneto-optical (MO) isolators on SiN platforms with record high performances based on standard silicon photonics foundry process and magneto-optical thin film deposition. We successfully grow high quality MO garnet thin films on SiN with large Faraday rotation up to -5900 deg/cm. We show a superior magneto-optical figure of merit (FoM) of MO/SiN waveguides compared to that of MO/SOI in an optimized device design. We demonstrate TM/TE mode broadband and narrow band optical isolators and circulators on SiN with high isolation ratio, low cross talk and low insertion loss. In particular, we observe 1 dB insertion loss and 28 dB isolation ratio in a SiN racetrack resonator-based isolator at 1570.2 nm wavelength. The low thermo-optic coefficient of SiN also ensures excellent temperature stability of the device. Our work paves the way for integration of high performance nonreciprocal photonic devices on SiN platforms. △ Less

Submitted 25 August, 2020; originally announced October 2020.

Design and study of a coronavirus-shaped metamaterial sensor stimulated by electromagnetic waves for rapid diagnosis of covid-19

Authors: Yadgar I. Abdulkarim, Halgurd N. Awl, Fahmi F. Muhammadsharif, Karzan R. Sidiq, Salah Raza Saeed, Muharrem Karaaslan, Shengxiang Huang, Heng Luo, Lianwen Deng

Abstract: We propose a new technique of utilizing metamaterials-based sensor for rapid diagnosis of covid-19 through electromagnetic-stimulated analysis of the blood drawn from the patient. The sensor was inspired by a coronavirus in plane-shaped design with presume that its circular structure might produce a broader interaction of the electromagnetic waves with the blood sample. The sensor was designed num… ▽ More We propose a new technique of utilizing metamaterials-based sensor for rapid diagnosis of covid-19 through electromagnetic-stimulated analysis of the blood drawn from the patient. The sensor was inspired by a coronavirus in plane-shaped design with presume that its circular structure might produce a broader interaction of the electromagnetic waves with the blood sample. The sensor was designed numerically and tested experimentally by evaluating variations in the reflection coefficient (S11) and transmission coefficient (S21) of the waves at resonant frequency. Results of covid-19 relevant blood sample showed a pronounced shift in the main resonant frequency of about 740 MHz compared to that of the control blood sample. We believe that with the help of the proposed sensor a significant breakthrough can be achieved for rapid diagnosis of covid-19 within few seconds. △ Less

Submitted 18 September, 2020; originally announced September 2020.

Self-formed 2D/3D Heterostructure on the Edge of 2D Ruddlesden-Popper Hybrid Perovskites Responsible for Intriguing Optoelectronic Properties and Higher Cell Efficiency

Authors: Zhaojun Qin, Shenyu Dai, Chalapathi Charan Gajjala, Chong Wang, Viktor G. Hadjiev, Guang Yang, Jiabing Li, Xin Zhong, Zhongjia Tang, Yan Yao, Arnold M. Guloy, Rohith Reddy, David Mayerich, Liangzi Deng, Qingkai Yu, Guoying Feng, Zhiming Wang, Jiming Bao

Abstract: The observation of low energy edge photoluminescence and its beneficial effect on the solar cell efficiency of Ruddlesden-Popper perovskites has unleashed an intensive research effort to reveal its origin. This effort, however, has been met with more challenges as the underlying material structure has still not been identified; new modellings and observations also do not seem to converge. Using 2D… ▽ More The observation of low energy edge photoluminescence and its beneficial effect on the solar cell efficiency of Ruddlesden-Popper perovskites has unleashed an intensive research effort to reveal its origin. This effort, however, has been met with more challenges as the underlying material structure has still not been identified; new modellings and observations also do not seem to converge. Using 2D (BA)2(MA)2Pb3Br10 as an example, we show that 3D MAPbBr3 is formed due to the loss of BA on the edge. This self-formed MAPbBr3 can explain the reported edge emission under various conditions, while the reported intriguing optoelectronic properties such as fast exciton trapping from the interior 2D perovskite, rapid exciton dissociation and long carrier lifetime can be understood via the self-formed 2D/3D lateral perovskite heterostructure. The 3D perovskite is identified by submicron infrared spectroscopy, the emergence of XRD signature from freezer-milled nanometer-sized 2D perovskite and its photoluminescence response to external hydrostatic pressure. The revelation of this edge emission mystery and the identification of a self-formed 2D/3D heterostructure provide a new approach to engineering 2D perovskites for high-performance optoelectronic devices. △ Less

Submitted 26 January, 2020; originally announced January 2020.