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Sapphire Photonic Crystal Fiber Sensor
Authors:
Mohan Wang,
Tongyu Liu,
Zipei Song,
Richard Reeves,
Frank P. Payne,
Igor N. Dyson,
Kaihui Zhang,
Tao Wang,
Jian Zhang,
Zhitai Jia,
Patrick S. Salter,
Martin J. Booth,
Julian A. J. Fells
Abstract:
Sapphire optical fiber shows great promise for remote sensing in extreme environments approaching 2000 degC, by using laser-processing to form a single-mode waveguide within it. However, for practical application, longer devices with high manufacturability and reliability are required. We report the design, modeling, fabrication, and optimization of an index-guiding sapphire photonic crystal fiber…
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Sapphire optical fiber shows great promise for remote sensing in extreme environments approaching 2000 degC, by using laser-processing to form a single-mode waveguide within it. However, for practical application, longer devices with high manufacturability and reliability are required. We report the design, modeling, fabrication, and optimization of an index-guiding sapphire photonic crystal fiber Bragg grating temperature sensor. The device is fabricated using femtosecond laser direct writing to inscribe both the photonic crystal waveguide and the Bragg grating. A spatial light modulator was used to compensate for the mismatch between the immersion objective and the high-index oil used. This improved the aspect ratio and suppressed cracking during fabrication, for higher reliability. The design results in a 6-fold reduction in fabrication time over an equivalent depressed cladding waveguide, significantly reducing the cost of manufacture. Devices up to 7 cm long were fabricated and spliced to standard single-mode fiber. The propagation loss was estimated to be 0.7 dB/cm and the Bragg gratings had a bandwidth of approximately 0.12 nm. Devices were tested in a furnace showing a temperature sensitivity of between 19.0-32.3 pm/degC over a range 25-1200 degC. These longer devices have the potential to enable practical high precision extreme temperature monitoring in many applications, with lower manufacturing cost and higher reliability.
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Submitted 3 May, 2026;
originally announced May 2026.
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Effects of 2.45 GHz radiofrequency upon Leuconostoc mesenteroides Glucose-6-phosphate dehydrogenase enzymatic activity
Authors:
G. Miño-Galaz,
V. Castro-Fernandez,
J. Martínez-Oyanedel,
R. Reeves,
J. Staforelli-Vivanco,
N. Martínez
Abstract:
In this report we evaluate the effect in the enzyme activity of Glucose 6-phosphate Dehydrogenase from Leuconostoc mesenteroides by irradiation with 2.45 GHz radiofrequency at a power output of 0.1 W during a 91 h period. The results show that the RF irradiation preserves the activity of treated samples of this enzyme with respect to a non-treated sample that instead suffer an increased rate of ac…
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In this report we evaluate the effect in the enzyme activity of Glucose 6-phosphate Dehydrogenase from Leuconostoc mesenteroides by irradiation with 2.45 GHz radiofrequency at a power output of 0.1 W during a 91 h period. The results show that the RF irradiation preserves the activity of treated samples of this enzyme with respect to a non-treated sample that instead suffer an increased rate of activity loss. Our estimates indicate that the enzyme activation is due to a non-thermal effect. The results are consistent with reports about the effect of 2.45 GHz radiation upon other enzymatic systems.
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Submitted 16 January, 2026;
originally announced January 2026.
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Design of the tertiary optical system for the Large Latin American Millimeter Array radio telescope
Authors:
Emiliano Rasztocky,
Matias Rolf Hampel,
Rodrigo Reeves,
Jacques R. D. Lepine,
Gustavo Esteban Romero
Abstract:
Many modern radio telescopes employ an observational strategy that involves maximizing the use of their available spaces (cabins), outfitting them with various receivers at different frequencies to detect incoming signals from the sky simultaneously or individually. The Large Latin American Millimeter Array (LLAMA), is a joint venture between Argentina and Brazil consisting of the installation and…
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Many modern radio telescopes employ an observational strategy that involves maximizing the use of their available spaces (cabins), outfitting them with various receivers at different frequencies to detect incoming signals from the sky simultaneously or individually. The Large Latin American Millimeter Array (LLAMA), is a joint venture between Argentina and Brazil consisting of the installation and operation of a 12-meter aperture Cassegrain telescope. It features three available cabins for instrumentation and plans to install six single-pixel heterodyne receivers, covering different bandwidths in the 30 to 950 GHz window of the electromagnetic spectrum, in its two lateral Nasmyth cabins at different phases of the project. Therefore, it is crucial not only to design a tertiary optical system that couples the antenna beam to those receivers, but also to do it in a scalable way. The primary goal for the design is to simultaneously maximize the antenna efficiency while minimizing optical aberrations for all receivers, both fundamental aspects for the optimal functioning of cutting-edge astronomical instruments. In this paper, we present the entire design process, starting from the quasi-optical approach based on the propagation of a fundamental Gaussian beam mode, continuing with the validation of the design based on physical optics simulations, and ending with a tolerance analysis of the system. As a result of this process, a frequency independent tertiary optical system has been achieved for almost all the receivers, which is expected to provide high optical performance for the radio telescope.
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Submitted 22 October, 2024;
originally announced October 2024.
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Reducing Richtmyer Meshkov Instability Jet Velocity via Inverse Design
Authors:
Dylan J. Kline,
Michael P. Hennessey,
David K. Amondson,
Steve Lin,
Michael D. Grapes,
Massimiliano Ferrucci,
Peggy Li,
H. Keo Springer,
Robert V. Reeves,
Kyle T. Sullivan,
Jonathan L. Belof
Abstract:
In this work, we detail a novel application of inverse design and advanced manufacturing to rapidly develop and experimentally validate modifications to a shaped charge jet analogue. The shaped charge jet analogue comprises a conical copper liner, high explosive (HE), and silicone buffer. We apply a genetic algorithm to determine an optimal buffer design that can be placed between the liner and th…
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In this work, we detail a novel application of inverse design and advanced manufacturing to rapidly develop and experimentally validate modifications to a shaped charge jet analogue. The shaped charge jet analogue comprises a conical copper liner, high explosive (HE), and silicone buffer. We apply a genetic algorithm to determine an optimal buffer design that can be placed between the liner and the HE that results in the largest possible change in jet velocity. The use of a genetic algorithm allows for discoveries of unintuitive, complex, yet optimal buffer designs. Experiments using the optimal design verified the effectiveness of the buffer and validated the modeling.
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Submitted 10 October, 2023;
originally announced October 2023.
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CLASS Observations of Atmospheric Cloud Polarization at Millimeter Wavelengths
Authors:
Yunyang Li,
John W. Appel,
Charles L. Bennett,
Ricardo Bustos,
David T. Chuss,
Joseph Cleary,
Jullianna Denes Couto,
Sumit Dahal,
Rahul Datta,
Rolando Dünner,
Joseph R. Eimer,
Thomas Essinger-Hileman,
Kathleen Harrington,
Jeffrey Iuliano,
Tobias A. Marriage,
Matthew A. Petroff,
Rodrigo A. Reeves,
Karwan Rostem,
Rui Shi,
Deniz A. N. Valle,
Duncan J. Watts,
Oliver F. Wolff,
Edward J. Wollack,
Zhilei Xu
Abstract:
The dynamic atmosphere imposes challenges to ground-based cosmic microwave background observation, especially for measurements on large angular scales. The hydrometeors in the atmosphere, mostly in the form of clouds, scatter the ambient thermal radiation and are known to be the main linearly polarized source in the atmosphere. This scattering-induced polarization is significantly enhanced for ice…
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The dynamic atmosphere imposes challenges to ground-based cosmic microwave background observation, especially for measurements on large angular scales. The hydrometeors in the atmosphere, mostly in the form of clouds, scatter the ambient thermal radiation and are known to be the main linearly polarized source in the atmosphere. This scattering-induced polarization is significantly enhanced for ice clouds due to the alignment of ice crystals under gravity, which are also the most common clouds seen at the millimeter-astronomy sites at high altitudes. This work presents a multifrequency study of cloud polarization observed by the Cosmology Large Angular Scale Surveyor (CLASS) experiment on Cerro Toco in the Atacama Desert of northern Chile, from 2016 to 2022, at the frequency bands centered around 40, 90, 150, and 220 GHz. Using a machine-learning-assisted cloud classifier, we made connections between the transient polarized emission found in all four frequencies with the clouds imaged by monitoring cameras at the observing site. The polarization angles of the cloud events are found to be mostly $90^\circ$ from the local meridian, which is consistent with the presence of horizontally aligned ice crystals. The 90 and 150 GHz polarization data are consistent with a power law with a spectral index of $3.90\pm0.06$, while an excess/deficit of polarization amplitude is found at 40/220 GHz compared with a Rayleigh scattering spectrum. These results are consistent with Rayleigh-scattering-dominated cloud polarization, with possible effects from supercooled water absorption and/or Mie scattering from a population of large cloud particles that contribute to the 220 GHz polarization.
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Submitted 13 September, 2023;
originally announced September 2023.
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The observation of electron trap liberation in MgF$_{2}$ doped with Yb$^{2+}$ using a two-color excitation experiment
Authors:
P. S. Senanayake,
J. P. R. Wells,
M. F. Reid,
G. Berden,
A. Meijerink,
R. J. Reeves
Abstract:
We utilize the optical transitions of Yb$^{2+}$ excited by an ultraviolet optical parametric amplifier to probe electron trap liberation in MgF$_{2}$ via the observation of a photoluminescence enhancement effect induced by a subsequent infrared pulse from a free-electron laser. The temperature dependence of the enhancement suggests that we liberate very shallow traps having a depth of approximatel…
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We utilize the optical transitions of Yb$^{2+}$ excited by an ultraviolet optical parametric amplifier to probe electron trap liberation in MgF$_{2}$ via the observation of a photoluminescence enhancement effect induced by a subsequent infrared pulse from a free-electron laser. The temperature dependence of the enhancement suggests that we liberate very shallow traps having a depth of approximately 17 cm$^{-1}$. The observed `trap spectrum' is consistent with a simple model of a Coulomb trap.
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Submitted 30 October, 2011;
originally announced October 2011.
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Impurity-trapped excitons and electron traps in CaF$_2$:Yb$^{2+}$ and SrF$_2$:Yb$^{2+}$ probed by transient photoluminescence enhancement
Authors:
P. S. Senanayake,
J. P. R. Wells,
M. F. Reid,
G. Berden,
A. Meijerink,
R. J. Reeves
Abstract:
CaF$_2$:Yb$^{2+}$ and SrF$_2$:Yb$^{2+}$ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals.
CaF$_2$:Yb$^{2+}$ and SrF$_2$:Yb$^{2+}$ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals.
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Submitted 6 October, 2011; v1 submitted 25 July, 2011;
originally announced July 2011.
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Transient photoluminescence enhancement as a probe of the structure of impurity-trapped excitons in CaF$_2$:Yb$^{2+}$
Authors:
Michael F. Reid,
Pubudu S. Senanayake,
Jon-Paul R. Wells,
Giel Berden,
Andries Meijerink,
Alexander J. Salkeld,
Chang-Kui Duan,
Roger J. Reeves
Abstract:
We demonstrate a direct measurement of the energy levels of impurity-trapped excitons in CaF$_2$:Yb$^{2+}$. The radically different radiative decay rates of the lowest exciton state and higher excited states enable the generation of a transient photoluminescence enhancement measured via a two-step excitation process. We observe sharp transitions arising from changes of state of localized electrons…
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We demonstrate a direct measurement of the energy levels of impurity-trapped excitons in CaF$_2$:Yb$^{2+}$. The radically different radiative decay rates of the lowest exciton state and higher excited states enable the generation of a transient photoluminescence enhancement measured via a two-step excitation process. We observe sharp transitions arising from changes of state of localized electrons, broad bands associated with changes of state of delocalized electrons, and broad bands arising from trap liberation.
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Submitted 23 September, 2011; v1 submitted 15 July, 2011;
originally announced July 2011.