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2 μm optical frequency comb generation via optical parametric oscillation from a lithium niobate optical superlattice box resonator

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Photonics Research 2022年第2期10卷 509-515页

作者： Xiaohan Wang Kunpeng Jia Mengwen Chen Shanshan Cheng Xin Ni Jian Guo Yihao Li Huaying Liu Liyun Hao Jian Ning Gang Zhao Xinjie Lv Shu-Wei Huang Zhenda Xie Shi-Ning Zhu National Laboratory of Solid State Microstructures School of Electronic Science and EngineeringSchool of PhysicsCollege of Engineering and Applied Sciencesand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China Department of Electrical Computer and Energy EngineeringUniversity of Colorado BoulderBoulderColorado 80309USA

Optical parametric oscillators(OPOs) can downconvert the pump laser to longer wavelengths with octave separation via χ^((2)), which is widely used for laser wavelength extension including mid-infrared(MIR) *** a process can be integrated in monolithic resonators, being compact and low in threshold. In this work, we show that the monolithic χ^((2))mini-OPO can also be used for optical frequency comb generation around 2096 nm and enters the boundary of MIR range. A new geometry called an optical superlattice box resonator is developed for this realization with near-material-limited quality factor of 4.0 × 10^(7). Only a continuous-wave near-infrared pump laser is required, with OPO threshold of 80 mW and output power up to 340 mW. Revival temporal profiles are measured at a detectable repetition frequency of 1.426 GHz, and narrow beat note linewidth of less than 10 Hz shows high comb coherence. These results are in good agreement with our simulation for a stable comb generation. Such an OPO-based comb source is useful for carbon dioxide sensing or the mine prospect applications and can be generalized to longer MIR wavelengths for general gas spectroscopy.

关键词： resonator optical pump

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Reversible magnetic domain reorientation induced by magnetic field pulses of fixed direction

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Physical Review B 2023年第6期108卷 064410-064410页

作者： Xichao Zhang Jing Xia Oleg A. Tretiakov Guoping Zhao Yan Zhou Masahito Mochizuki Xiaoxi Liu Motohiko Ezawa Department of Applied Physics Waseda University Okubo Shinjuku-ku Tokyo 169-8555 Japan Department of Electrical and Computer Engineering Shinshu University 4-17-1 Wakasato Nagano 380-8553 Japan School of Physics The University of New South Wales Sydney 2052 Australia College of Physics and Electronic Engineering Sichuan Normal University Chengdu 610068 China School of Science and Engineering The Chinese University of Hong Kong Shenzhen Guangdong 518172 China Department of Applied Physics The University of Tokyo 7-3-1 Hongo Tokyo 113-8656 Japan

Nanoscale magnetic domains with controllable configurations could be used for classical and quantum applications, where the switching of magnetization configurations is an essential operation for information processing. Here, we report that the magnetic domain reorientation in a notched ferromagnetic nanotrack can be realized and effectively controlled by applying uniform magnetic field pulses in a fixed in-plane direction perpendicular to the nanotrack. Our micromagnetic simulation results show that the configurations of magnetic domains in the notched nanotrack can be switched between a head-to-head state and a tail-to-tail state in a reversible manner driven by magnetic field pulses, while it is unnecessary to reverse the direction of the magnetic field. Such a unique magnetic domain reorientation dynamics is found to depend on magnetic parameters and nanotrack geometries. The reorientation dynamics of magnetic domains also depends on the strength and length of the applied magnetic-field pulse. In addition, we point out that the notches at the center of the nanotrack play an important role for the stabilization of the head-to-head and tail-to-tail states during the magnetic domain reorientation. We also qualitatively explain the field-induced reorientation phenomenon with a simplified two-dimensional macrospin model. Our results may make it possible to build spintronic devices driven by a fixed magnetic field. Our findings may also motivate future studies to investigate the classical and quantum applications based on nanoscale magnetic domains.

关键词： Magnetization dynamics Magnetization switching Micromagnetism Spin dynamics Spintronics Micromagnetic modeling

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Qubit-state purity oscillations from anisotropic transverse noise

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Physical Review A 2025年第3期111卷 032420-032420页

作者： David A. Rower Kotaro Hida Lamia Ateshian Helin Zhang Junyoung An Max Hays Sarah E. Muschinske Christopher M. McNally Samuel C. Alipour-Fard Department of Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Applied Physics Graduate School of Engineering The University of Tokyo Bunkyo-ku Tokyo 113-8656 Japan Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Center for Theoretical Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA The NSF AI Institute for Artificial Intelligence and Fundamental Interactions Cambridge Massachusetts 02139 USA

We explore the dynamics of qubit-state purity in the presence of transverse noise that is anisotropically distributed in the Bloch-sphere XY plane. We perform Ramsey experiments with noise injected along a fixed laboratory-frame axis and observe oscillations in the purity at twice the qubit frequency arising from the intrinsic qubit Larmor precession. We probe the oscillation dependence on the noise anisotropy, orientation, and power spectral density, using a low-frequency fluxonium qubit. Our results elucidate the impact of transverse noise anisotropy on qubit decoherence and may be useful for disentangling charge and flux noise in superconducting quantum circuits.

关键词： Qubits

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Large tuning of the optical properties of nanoscale NdNiO3 via electron doping

arXiv

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arXiv 2024年

作者： Jin, Yeonghoon Qu, Teng Kumar, Siddharth Kubzdela, Nicola Tsai, Cheng-Chia De Li, Tai Ramanathan, Shriram Yu, Nanfang Kats, Mikhail A. Department of Electrical and Computer Engineering University of Wisconsin-Madison Wisconsin53706 United States Department of Applied Physics and Applied Mathematics Columbia University New York10027 United States Department of Electrical and Computer Engineering Rutgers The State University of New Jersey New Jersey08854 United States CUNY Graduate Center Advanced Science Research Center New York11201 United States Department of Material Science and Engineering University of Wisconsin-Madison Wisconsin53706 United States

We synthesized crystalline films of neodymium nickel oxide (NdNiO3), a perovskite quantum material, switched the films from a metal phase (intrinsic) into an insulator phase (electron-doped) by field-driven lithium-ion intercalation, and characterized their structural and optical properties. Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) showed that the intercalation process resulted in a gradient of the dopant concentration along the thickness direction of the films, turning the films into insulator-metal bilayers. We used variable-angle spectroscopic ellipsometry to measure the complex refractive indices of the metallic and insulating phases of NdNiO3. The insulator phase has a refractive index of n ~ 2 and low absorption in the visible and near infrared, and analysis of the complex refractive indices indicated that the band gap of the insulating phase is roughly 3-4 eV. electrical control of the optical band gap, with corresponding large changes to the optical refractive indices, creates new opportunities for tunable optics. Copyright © 2024, The Authors. All rights reserved.

关键词： Energy gap

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Nernst-Ettingshausen effect in thin Pt and W films at low temperatures

arXiv

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arXiv 2023年

作者： Luo, Renjie Legvold, Tanner J. Chen, Liyang Natelson, Douglas Department of Physics and Astronomy Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States

As spin caloritronic measurements become increasingly common techniques for characterizing material properties, it is important to quantify potentially confounding effects. We report measurements of the Nernst-Ettingshausen response from room temperature to 5 K in thin film wires of Pt and W, metals commonly used as inverse spin Hall detectors in spin Seebeck characterization. Johnson-Nyquist noise thermometry is used to assess the temperature change of the metals with heater power at low temperatures, and the thermal path is analyzed via finite-element modeling. The Nernst-Ettingshausen response of W is found to be approximately temperature-independent, while the response of Pt increases at low temperatures. These results are discussed in the context of theoretical expectations and the possible role of magnetic impurities in Pt. Copyright © 2023, The Authors. All rights reserved.

关键词： Inverse problems

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Generation of Multiple Obstruction-Free Channels for Free Space Optical Communication

Generation of Multiple Obstruction-Free Channels for Free Sp...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Reza, Saad Bin Ali Burger, Milos Bassène, Pascal Nutting, Tanner Jovanovic, Igor N'Gom, Moussa Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute 110 8th street TroyNY12180 United States Department of Nuclear Engineering and Radiological Sciences University of Michigan Ann ArborMI48109 United States Gérard Mourou Center for Ultrafast Optical Science University of Michigan Ann ArborMI48109 United States Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute 110 8th street TroyNY12180 United States

Plasma filaments generated by ultrafast beams with orbital angular momentum can simultaneously clear two cylindrical transmission channels, within which an annular beam can propagate free of obstructions. © Optic...

ISBN: (纸本)9781957171258

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Transferable polychromatic optical encoder for neural networks

arXiv

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arXiv 2024年

作者： Choi, Minho Xiang, Jinlin Wirth-Singh, Anna Baek, Seung-Hwan Shlizerman, Eli Majumdar, Arka Department of Electrical and Computer Engineering University of Washington SeattleWA98103 United States Department of Physics University of Washington SeattleWA98103 United States Department of Computer Science and Engineering Pohang University of Science and Technology Gyeongbuk Pohang37673 Korea Republic of Department of Applied Mathematics University of Washington SeattleWA98103 United States

Artificial neural networks (ANNs) have fundamentally transformed the field of computer vision, providing unprecedented performance. However, these ANNs for image processing demand substantial computational resources, often hindering real-time operation. In this paper, we demonstrate an optical encoder that can perform convolution simultaneously in three color channels during the image capture, effectively implementing several initial convolutional layers of a ANN. Such an optical encoding results in 24, 000× reduction in computational operations, with a state-of-the art classification accuracy (∼ 73.2%) in free-space optical system. In addition, our analog optical encoder, trained for CIFAR-10 data, can be transferred to the ImageNet subset, High-10, without any modifications, and still exhibits moderate accuracy. Our results evidence the potential of hybrid optical/digital computer vision system in which the optical frontend can pre-process an ambient scene to reduce the energy and latency of the whole computer vision system. Copyright © 2024, The Authors. All rights reserved.

关键词： Object detection

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Demonstration of a polarization-agnostic geometric phase in nonlocal metasurfaces

Demonstration of a polarization-agnostic geometric phase in ...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Overvig, Adam C. Kasahara, Y. Alu, Andrea Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Department of Electrical and Computer Engineering The University of Texas at Austin AustinTX78712 United States Physics Program Graduate Center of the City University of New York New YorkNY10016 United States

We theoretically propose and experimentally demonstrate nonlocal metasurfaces rationally designed using symmetry-breaking principles to manipulate the optical wavefront with a geometric phase selective to custom ellip...

ISBN: (纸本)9781957171258

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Secrecy Outage Probability of Full-Duplex Relaying Vehicular Networks 10

Secrecy Outage Probability of Full-Duplex Relaying Vehicular...

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10th International Japan-Africa Conference on Electronics, Communications, and Computations, JAC-ECC 2022

作者： Abd El Ghafour, Mohamed G. Abd El-Malek, Ahmed H. Hassan, Ola E. Abo-Zahhad, Mohammed Alexandria University Faculty of Engineering Department of Engineering Mathematics and Physics Alexandria21544 Egypt Egypt-Japan University of Science & Technology School of Electronics Communications & Computer Engineering Alexandria21934 Egypt Arab Academy for Science Technology & Maritime Transport Basic and Applied Science Department Smart Village Campus Giza12577 Egypt Assiut University Faculty of Engineering Electrical Engineering Department Assiut71515 Egypt

ISBN: (纸本)9781665464635

This paper investigates the secrecy performance of full-duplex cooperative vehicular relaying networks under passive eavesdropping attacks in the presence of co-channel interference. In the considered system model, a static source communicates with a static destination through a mobile full-duplex relay in the presence of a mobile passive eavesdropper and a static co-channel interferer. A closed-form expression for the exact secrecy outage probability of the system is derived for the Nakagami-m fading environment. Hence, the asymptotic secrecy outage probability is obtained at high signal-to-noise values. Numerical and Simulation results are obtained to validate the derived analytical expressions. © 2022 IEEE.

关键词： Signal to noise ratio

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Comparative Evaluation between Accelerated RISC- V and ARM AI Inference Machines

Comparative Evaluation between Accelerated RISC- V and ARM A...

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IEEE World Symposium on Communication engineering (WSCE)

作者： Vasileios Christofas Petros Amanatidis Dimitris Karampatzakis Thomas Lagkas Sotirios K. Goudos Konstantinos E. Psannis Panagiotis Sarigiannidis Department of Computer Science International Hellenic University Kavala Greece Department of Physics Aristotle University of Thessaloniki Thessaloniki Greece Department of Applied Informatics University of Macedonia Thessaloniki Greece Department of Electrical and Computer Engineering University of Western Macedonia Kozani Greece

Embedded AI development has been rapidly im-proving for the past few years and has had a great impact on edge AI networks. However, as neural networks become deeper and deeper it becomes more difficult to execute complicated tasks without sacrificing a good amount of power and performance. In this paper, we make a comparative evaluation between two AI acceleration devices. The first one features a RISC- V 64-bit processor while the other one is ARM powered. These devices are combined with AI co-processors, or ASICs, with computer vision capabilities. Our benchmark consists of a simple classification task split into multiple versions. The results showed that the RISC- V inference machine had 4 times lower consumption while the ARM machine was up to 15 times faster in our largest network. We discuss the results in great detail while keeping our focus on all aspects equally. Finally, we make recommendations based on their usage and application.

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