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Unravelling and circumventing failure mechanisms in chalcogenide optical phase change materials
Authors:
Cosmin Constantin Popescu,
Kiumars Aryana,
Brian Mills,
Tae Woo Lee,
Louis Martin-Monier,
Luigi Ranno,
Jia Xu Brian Sia,
Khoi Phuong Dao,
Hyung-Bin Bae,
Vladimir Liberman,
Steven Vitale,
Myungkoo Kang,
Kathleen A. Richardson,
Carlos A. Ríos Ocampo,
Dennis Calahan,
Yifei Zhang,
William M. Humphreys,
Hyun Jung Kim,
Tian Gu,
Juejun Hu
Abstract:
Chalcogenide optical phase change materials (PCMs) have garnered significant interest for their growing applications in programmable photonics, optical analog computing, active metasurfaces, and beyond. Limited endurance or cycling lifetime is however increasingly becoming a bottleneck toward their practical deployment for these applications. To address this issue, we performed a systematic study…
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Chalcogenide optical phase change materials (PCMs) have garnered significant interest for their growing applications in programmable photonics, optical analog computing, active metasurfaces, and beyond. Limited endurance or cycling lifetime is however increasingly becoming a bottleneck toward their practical deployment for these applications. To address this issue, we performed a systematic study elucidating the cycling failure mechanisms of Ge$_2$Sb$_2$Se$_4$Te (GSST), a common optical PCM tailored for infrared photonic applications, in an electrothermal switching configuration commensurate with their applications in on-chip photonic devices. We further propose a set of design rules building on insights into the failure mechanisms, and successfully implemented them to boost the endurance of the GSST device to over 67,000 cycles.
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Submitted 18 September, 2024;
originally announced September 2024.
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An Open-Source Multi-functional Testing Platform for Optical Phase Change Materials
Authors:
Cosmin-Constantin Popescu,
Khoi Phuong Dao,
Luigi Ranno,
Brian Mills,
Louis Martin,
Yifei Zhang,
David Bono. Brian Neltner,
Tian Gu,
Juejun Hu,
Kiumars Aryana,
William M. Humphreys,
Hyun Jung Kim,
Steven Vitale,
Paul Miller,
Christopher Roberts,
Sarah Geiger,
Dennis Callahan,
Michael Moebius,
Myungkoo Kang,
Kathleen Richardson,
Carlos A. Ríos Ocampo
Abstract:
Owing to their unique tunable optical properties, chalcogenide phase change materials are increasingly being investigated for optics and photonics applications. However, in situ characterization of their phase transition characteristics is a capability that remains inaccessible to many researchers. In this article, we introduce a multi-functional silicon microheater platform capable of in situ mea…
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Owing to their unique tunable optical properties, chalcogenide phase change materials are increasingly being investigated for optics and photonics applications. However, in situ characterization of their phase transition characteristics is a capability that remains inaccessible to many researchers. In this article, we introduce a multi-functional silicon microheater platform capable of in situ measurement of structural, kinetic, optical, and thermal properties of these materials. The platform can be fabricated leveraging industry-standard silicon foundry manufacturing processes. We fully open-sourced this platform, including complete hardware design and associated software codes.
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Submitted 12 July, 2023;
originally announced July 2023.
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Muon-spin relaxation investigation of magnetic bistability in a crystalline organic radical compound
Authors:
Alberto Hernandez-Melian,
Benjamin M. Huddart,
Francis L. Pratt,
Stephen J. Blundell,
Michelle B. Mills,
Harrison K. S. Young,
Kathryn E. Preuss,
Tom Lancaster
Abstract:
We present the results of a muon-spin relaxation ($μ^{+}$SR) investigation of the crystalline organic radical compound 4-(2-benzimidazolyl)-1,2,3,5-dithiadiazolyl (HbimDTDA), in which we demonstrate the hysteretic magnetic switching of the system that takes place at $T = 274 \pm 11\,\mathrm{K}$ caused by a structural phase transition. Muon-site analysis using electronic structure calculations sugg…
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We present the results of a muon-spin relaxation ($μ^{+}$SR) investigation of the crystalline organic radical compound 4-(2-benzimidazolyl)-1,2,3,5-dithiadiazolyl (HbimDTDA), in which we demonstrate the hysteretic magnetic switching of the system that takes place at $T = 274 \pm 11\,\mathrm{K}$ caused by a structural phase transition. Muon-site analysis using electronic structure calculations suggests a range of candidate muon stopping sites. The sites are numerous and similar in energy but, significantly, differ between the two structural phases of the material. Despite the difference in the sites, the muon remains a faithful probe of the transition, revealing a dynamically-fluctuating magnetically disordered state in the low-temperature structural phase. In contrast, in the high temperature phase the relaxation is caused by static nuclear moments, with rapid electronic dynamics being motionally narrowed from the muon spectra.
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Submitted 28 November, 2022;
originally announced November 2022.
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Probing magnetic order and disorder in the one-dimensional molecular spin chains CuF2(pyz) and [Ln(hfac)3(boaDTDA)]n (Ln=Sm, La) using implanted muons
Authors:
T. Lancaster,
B. M. Huddart,
R. C. Williams,
F. Xiao,
K. J. A. Franke,
P. J. Baker,
F. L. Pratt,
S. J. Blundell,
J. A. Schlueter,
M. B. Mills,
A. C. Maahs,
K. E. Preuss
Abstract:
We present the results of muon-spin relaxation ($μ^{+}$SR) measurements on antiferromagnetic and ferromagnetic spin chains. In antiferromagnetic CuF$_{2}$(pyz) we identify a transition to long range magnetic order taking place at $T_{\mathrm{N}} = 0.6(1)$ K, allowing us to estimate a ratio with the intrachain exchange of $T_{\mathrm{N}}/|J| \approx 0.1$ and the ratio of interchain to intrachain ex…
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We present the results of muon-spin relaxation ($μ^{+}$SR) measurements on antiferromagnetic and ferromagnetic spin chains. In antiferromagnetic CuF$_{2}$(pyz) we identify a transition to long range magnetic order taking place at $T_{\mathrm{N}} = 0.6(1)$ K, allowing us to estimate a ratio with the intrachain exchange of $T_{\mathrm{N}}/|J| \approx 0.1$ and the ratio of interchain to intrachain exchange coupling as $|J'/J| \approx 0.05$. The ferromagnetic chain [Sm(hfac)$_{3}$(boaDTDA)]$_{n}$ undergoes an ordering transition at $T_{\mathrm{c}}=2.8(1)$ K, seen via a broad freezing of dynamic fluctuations on the muon (microsecond) timescale and implying $T_{\mathrm{c}}/|J| \approx 0.6$. The ordered radical moment continues to fluctuate on this timescale down to 0.3 K, while the Sm moments remain disordered. In contrast, the radical spins in [La(hfac)$_{3}$(boaDTDA)]$_{n}$ remain magnetically disordered down to $T=0.1$ K suggesting $T_{\mathrm{c}}/|J| < 0.17$.
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Submitted 13 May, 2019;
originally announced May 2019.
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An all-optical spatial light modulator for field-programmable silicon photonic circuits
Authors:
Roman Bruck,
Kevin Vynck,
Philippe Lalanne,
Ben Mills,
David J. Thomson,
Goran Z. Mashanovich,
Graham T. Reed,
Otto L. Muskens
Abstract:
Reconfigurable photonic devices capable of routing the flow of light enable flexible integrated-optic circuits that are not hard-wired but can be externally controlled. Analogous to free-space spatial light modulators, we demonstrate all-optical wavefront shaping in integrated silicon-on-insulator photonic devices by modifying the spatial refractive index profile of the device employing ultraviole…
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Reconfigurable photonic devices capable of routing the flow of light enable flexible integrated-optic circuits that are not hard-wired but can be externally controlled. Analogous to free-space spatial light modulators, we demonstrate all-optical wavefront shaping in integrated silicon-on-insulator photonic devices by modifying the spatial refractive index profile of the device employing ultraviolet pulsed laser excitation. Applying appropriate excitation patterns grants us full control over the optical transfer function of telecommunication-wavelength light travelling through the device, thus allowing us to redefine its functionalities. As a proof-of-concept, we experimentally demonstrate routing of light between the ports of a multimode interference power splitter with more than 97% total efficiency and negligible losses. Wavefront shaping in integrated photonic circuits provides a conceptually new approach toward achieving highly adaptable and field-programmable photonic circuits with applications in optical testing and data communication.
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Submitted 25 January, 2016;
originally announced January 2016.
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Ultrafast Photomodulation Spectroscopy: a device-level tool for characterizing the flow of light in integrated photonic circuits
Authors:
Roman Bruck,
Ben Mills,
David J. Thomson,
Frederic Y. Gardes,
Youfang Hu,
Graham T. Reed,
Otto L. Muskens
Abstract:
Advances in silicon photonics have resulted in rapidly increasing complexity of integrated circuits. New methods are desirable that allow direct characterization of individual optical components in-situ, without the need for additional fabrication steps or test structures. Here, we present a new device-level method for characterization of photonic chips based on a highly localized modulation in th…
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Advances in silicon photonics have resulted in rapidly increasing complexity of integrated circuits. New methods are desirable that allow direct characterization of individual optical components in-situ, without the need for additional fabrication steps or test structures. Here, we present a new device-level method for characterization of photonic chips based on a highly localized modulation in the device using pulsed laser excitation. Optical pumping perturbs the refractive index of silicon, providing a spatially and temporally localized modulation in the transmitted light enabling time- and frequency-resolved imaging. We demonstrate the versatility of this all-optical modulation technique in imaging and in quantitative characterization of a variety of properties of silicon photonic devices, ranging from group indices in waveguides, quality factors of a ring resonator to the mode structure of a multimode interference device. Ultrafast photomodulation spectroscopy provides important information on devices of complex design, and is easily applicable for testing on the device-level.
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Submitted 7 June, 2014;
originally announced June 2014.
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An ultrafast reconfigurable nanophotonic switch using wavefront shaping of light in a nonlinear nanomaterial
Authors:
Tom Strudley,
Roman Bruck,
Ben Mills,
Otto L. Muskens
Abstract:
We demonstrate a new concept for reconfigurable nanophotonic devices exploiting ultrafast nonlinear control of shaped wavefronts in a multimode nanomaterial consisting of semiconductor nanowires. Femtosecond pulsed laser excitation of the nanowire mat is shown to provide an efficient nonlinear mechanism to control both destructive and constructive interference in a shaped wavefront. Modulations of…
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We demonstrate a new concept for reconfigurable nanophotonic devices exploiting ultrafast nonlinear control of shaped wavefronts in a multimode nanomaterial consisting of semiconductor nanowires. Femtosecond pulsed laser excitation of the nanowire mat is shown to provide an efficient nonlinear mechanism to control both destructive and constructive interference in a shaped wavefront. Modulations of up to 63% are induced by optical pumping, due to a combination of multimode dephasing and induced transient absorption. We show that part of the nonlinear phase dynamics can be inverted to provide a dynamical revival of the wavefront into an optimized spot with up to 18% increase of the peak to background ratio caused by pulsed laser excitation. The concepts of multimode nonlinear switching demonstrated here are generally extendable to other photonic and plasmonic systems and enable new avenues for ultrafast and reconfigurable nanophotonic devices.
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Submitted 28 September, 2014; v1 submitted 1 December, 2013;
originally announced December 2013.
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Ultrafast plasmonics using transparent conductive oxide hybrids in the epsilon near-zero regime
Authors:
Daniel Traviss,
Roman Bruck,
Ben Mills,
Martina Abb,
Otto L. Muskens
Abstract:
The dielectric response of transparent conductive oxides near the bulk plasmon frequency is characterized by a refractive index less than vacuum. In analogy with x-ray optics, it is shown that this regime results in total external reflection and air-guiding of light. In addition, the strong reduction of the wavevector in the ITO below that of free space enables a new surface plasmon polariton mode…
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The dielectric response of transparent conductive oxides near the bulk plasmon frequency is characterized by a refractive index less than vacuum. In analogy with x-ray optics, it is shown that this regime results in total external reflection and air-guiding of light. In addition, the strong reduction of the wavevector in the ITO below that of free space enables a new surface plasmon polariton mode which can be excited without requiring a prism or grating coupler. Ultrafast control of the surface plasmon polariton mode is achieved with a modulation amplitude reaching 20%.
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Submitted 26 February, 2013;
originally announced February 2013.