Multimode optical interferometers represent the most viable platforms for the successful implementation of several quantum information schemes that take advantage of optical processing.Examples range from quantum comm...Multimode optical interferometers represent the most viable platforms for the successful implementation of several quantum information schemes that take advantage of optical processing.Examples range from quantum communication and sensing,to computation,including optical neural networks,optical reservoir computing,or simulation of complex physical systems.The realization of such routines requires high levels of control and tunability of the parameters that define the operations carried out by the device.This requirement becomes particularly crucial in light of recent technological improvements in integrated photonic technologies,which enable the implementation of progressively larger circuits embedding a considerable amount of tunable parameters.We formulate efficient procedures for the characterization of optical circuits in the presence of imperfections that typically occur in physical experiments,such as unbalanced losses and phase instabilities in the input and output collection stages.The algorithm aims at reconstructing the transfer matrix that represents the optical interferometer without making any strong assumptions about its internal structure and encoding.We show the viability of this approach in an experimentally relevant scenario,defined by a tunable integrated photonic circuit,and we demonstrate the effectiveness and robustness of our method.Our findings can find application in a wide range of optical setups,based on both bulk and integrated configurations.展开更多
Characterization of power transistors is an indispensable step in the design of radio frequency and mi- crowave power amplifiers. A full harmonic load-pull measurement setup is normally required for the accurate and c...Characterization of power transistors is an indispensable step in the design of radio frequency and mi- crowave power amplifiers. A full harmonic load-pull measurement setup is normally required for the accurate and comprehensive characterization of RF power transistors. The setup is usually highly complex, leading to a rela- tively high hardware cost and low measurement throughput. This paper presents X-parameter measurement on a gallium nitride （GaN） high-electron-mobility transistor and studies the potential of utilizing an X-parameter-based modeling technique to highly reduce the complexity of the harmonic load-pull measurement setup for transistor characterization. During the X-parameter measurement and characterization, load impedance of the device is tuned and controlled only at the fundamental frequency and is left uncontrolled at other higher harmonics. However, it proves preliminarily that the extracted X-parameters can still predict the behavior of the device with moderate to high accuracy, when the load impedance is tuned up to the third-order harmonic frequency. It means that a fundamental-only load-pull test setup is already enough even though the device is to be characterized under load tuning up to the third-order harmonic frequency, by utilizing X-parameters.展开更多
A high-speed silicon modulator with broad optical bandwidth is proposed based on a symmetrically configured Mach- Zehnder interferometer. Careful phase bias control and traveling-wave design are used to improve the hi...A high-speed silicon modulator with broad optical bandwidth is proposed based on a symmetrically configured Mach- Zehnder interferometer. Careful phase bias control and traveling-wave design are used to improve the high-speed perfor- mance. Over a broadband wavelength range, high-speed operation up to 30 Gbit/s with a 4.5 dB-5.5 dB extinction ratio is experimentally demonstrated with a low driving voltage of 3 V.展开更多
Electrocatalysis offers a sustainable route for olefin oxidation,attracting considerable attention.This review presents a comprehensive analysis of core elements governing olefin electrocatalyst performance and mechan...Electrocatalysis offers a sustainable route for olefin oxidation,attracting considerable attention.This review presents a comprehensive analysis of core elements governing olefin electrocatalyst performance and mechanism,examining catalyst microenvironment,reaction-equipment compatibility,and in-situ characterization.Focusing on catalyst design,it analyzes key performance and mechanistic factors including morphology/dimensions,metal/metal oxide composition,valence states,crystal facets,coordination environment,and alloy synergy.The review also summarizes and prospects emerging catalyst types,coupled reaction systems,reactor design,and in-situ characterization techniques.It holds significant value for the targeted development and industrial application of olefin epoxidation catalysts and broader organic synthesis.展开更多
基金supported by the European Union’s Horizon 2020 research and innovation program through the FET project Photonic Quantum Sampling machine(Grant Agreement No.899544)Ministero dell’Istruzione,dell’Universitàe della Ricerca via Project PRIN 2017 Taming Complexity via Quantum Strategies a Hybrid Integrated Photonic approach(Id No.2017SRNBRK).
文摘Multimode optical interferometers represent the most viable platforms for the successful implementation of several quantum information schemes that take advantage of optical processing.Examples range from quantum communication and sensing,to computation,including optical neural networks,optical reservoir computing,or simulation of complex physical systems.The realization of such routines requires high levels of control and tunability of the parameters that define the operations carried out by the device.This requirement becomes particularly crucial in light of recent technological improvements in integrated photonic technologies,which enable the implementation of progressively larger circuits embedding a considerable amount of tunable parameters.We formulate efficient procedures for the characterization of optical circuits in the presence of imperfections that typically occur in physical experiments,such as unbalanced losses and phase instabilities in the input and output collection stages.The algorithm aims at reconstructing the transfer matrix that represents the optical interferometer without making any strong assumptions about its internal structure and encoding.We show the viability of this approach in an experimentally relevant scenario,defined by a tunable integrated photonic circuit,and we demonstrate the effectiveness and robustness of our method.Our findings can find application in a wide range of optical setups,based on both bulk and integrated configurations.
文摘Characterization of power transistors is an indispensable step in the design of radio frequency and mi- crowave power amplifiers. A full harmonic load-pull measurement setup is normally required for the accurate and comprehensive characterization of RF power transistors. The setup is usually highly complex, leading to a rela- tively high hardware cost and low measurement throughput. This paper presents X-parameter measurement on a gallium nitride （GaN） high-electron-mobility transistor and studies the potential of utilizing an X-parameter-based modeling technique to highly reduce the complexity of the harmonic load-pull measurement setup for transistor characterization. During the X-parameter measurement and characterization, load impedance of the device is tuned and controlled only at the fundamental frequency and is left uncontrolled at other higher harmonics. However, it proves preliminarily that the extracted X-parameters can still predict the behavior of the device with moderate to high accuracy, when the load impedance is tuned up to the third-order harmonic frequency. It means that a fundamental-only load-pull test setup is already enough even though the device is to be characterized under load tuning up to the third-order harmonic frequency, by utilizing X-parameters.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2012AA012202)the National Basic Research Program of China(Grant No.2011CB301701)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KGCX2-EW-102)the National Natural Science Foundation of China(Grant Nos.61107048 and 61275065)
文摘A high-speed silicon modulator with broad optical bandwidth is proposed based on a symmetrically configured Mach- Zehnder interferometer. Careful phase bias control and traveling-wave design are used to improve the high-speed perfor- mance. Over a broadband wavelength range, high-speed operation up to 30 Gbit/s with a 4.5 dB-5.5 dB extinction ratio is experimentally demonstrated with a low driving voltage of 3 V.
基金supported by the National Key R&D Program of China(No.92461304)the National Natural Science Foundation of China(No.U24A20479)Henan Province Key Research and Development and Promotion Program(Scientific and Technological Breakthrough Project:252102230078).
文摘Electrocatalysis offers a sustainable route for olefin oxidation,attracting considerable attention.This review presents a comprehensive analysis of core elements governing olefin electrocatalyst performance and mechanism,examining catalyst microenvironment,reaction-equipment compatibility,and in-situ characterization.Focusing on catalyst design,it analyzes key performance and mechanistic factors including morphology/dimensions,metal/metal oxide composition,valence states,crystal facets,coordination environment,and alloy synergy.The review also summarizes and prospects emerging catalyst types,coupled reaction systems,reactor design,and in-situ characterization techniques.It holds significant value for the targeted development and industrial application of olefin epoxidation catalysts and broader organic synthesis.
