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Analysis of iris-loaded resonance cavity in miniaturized maser

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Chinese Physics B 2020年第5期29卷 188-193页

作者： Zu-Gen Guo Yong Zhang Tao Tang Zhan-Liang Wang Yu-Bin Gong Fei Xiao Hua-Rong Gong National Key Laboratory of Science and Technology on Vacuum Electronics School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu 610054China

The size reduction of atomic clocks is a long-standing research *** atomic clocks such as passive hydrogen masers(PHMs)and compact rubidium masers(CRMs)use iris-loaded resonance cavities(IRCs)as their microwave cavities because they can dramatically reduce the radical sizes of the atomic *** this paper,the electromagnetic characteristic of the IRC is investigated by a theoretical model based on electromagnetic field *** formulas to calculate the resonance frequency,quality factor,and magnetic energy filling factor are *** relationship between the IRC structure and its electromagnetic characteristic is *** theoretical calculation results accord well with the electromagnetic software simulations and experimental *** results in this paper should be helpful in understanding the physical mechanism of the IRC and designing the atomic clocks.

关键词： maser iris-loaded resonance cavity resonance frequency quality factor magnetic energy filling factor

Double-triangular whispering-gallery mode lasing from a hexagonal GaN microdisk grown on graphene

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Journal of Materials Science & Technology 2020年第18期52卷 140-145页

作者： Geng He Feifei Qin Chunxiang Xu Chinhua Wang Yu Xu Bing Cao Ke Xu School of Optoelectronic Science and Engineering Soochow UniversitySuzhou 215006China Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China Soochow UniversitySuzhou 215006China State Key Laboratory of Bioelectronics Department of PhysicsSoutheast UniversityNanjing 210096China Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO) Chinese Academy of Sciences(CAS)Suzhou 215123China Suzhou Nanowin Science and Technology Co Ltd Suzhou 215123China

The III-nitride semiconductor microdisk laser exhibits high quality factor and low excitation threshold with broad development potential in the field of nanophotonics such as nanoscale light-emitting devices and on-chip optical *** far,many works have been focused on process synthesis and nanostructural design of microdisk ***,there are still some limitations in the existing optical resonance mode which is an important internal influence factor for lasing *** this work,a new double-triangular whispering-gallery mode(D3-WGM)lasing from a hexagonal GaN microdisk with a high quality(Q)factor of 3049 and an excitation threshold of around 11.5μW has been experimentally *** addition,the optical properties of hexagonal-WGM(6-WGM),triangular-WGM(3-WGM)and D3-WGM lasing from microdisk are explored by numerical calculation and Comsol *** results confirm that the D3-WGM lasing has its own significant performance advantages,namely high Q factor and easy light *** on this novel laser mode characteristic,microcavity lasers are expected to be further developed and applied in the field of nanophotonics.

关键词： GaN microdisks Graphene Whispering gallery mode quality factor

Momentum-space imaging spectroscopy for the study of nanophotonic materials

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Science Bulletin 2021年第8期66卷 824-838,M0004页

作者： Yiwen Zhang Maoxiong Zhao Jiajun Wang Wenzhe Liu Bo Wang Songting Hu Guopeng Lu Ang Chen Jing Cui Weiyi Zhang Chia Wei Hsu Xiaohan Liu Lei Shi Haiwei Yin Jian Zi Department of Physics Key Laboratory of Micro-and Nano-Photonic Structures(Ministry of Education)and State Key Laboratory of Surface PhysicsFudan UniversityShanghai 200433China Shanghai Engineering Research Center of Optical Metrology for Nano-fabrication(SERCOM) Shanghai 200433China Ming Hsieh Department of Electrical Engineering University of Southern CaliforniaLos AngelesCA 90089USA Collaborative Innovation Center of Advanced Microstructures Fudan UniversityShanghai 200433China

The novel phenomena in nanophotonic materials, such as the angle-dependent reflection and negative refraction effect, are closely related to the photonic dispersions EepT. EepT describes the relation between energy E and momentum p of photonic eigenmodes, and essentially determines the optical properties of materials. As EepT is defined in momentum space(k-space), the experimental method to detect the energy distribution, that is the spectrum, in a momentum-resolved manner is highly required. In this review, the momentum-space imaging spectroscopy(MSIS) system is presented, which can directly study the spectral information in momentum space. Using the MSIS system, the photonic dispersion can be captured in one shot with high energy and momentum resolution. From the experimental momentumresolved spectrum data, other key features of photonic eigenmodes, such as quality factors and polarization states, can also be extracted through the post-processing algorithm based on the coupled mode theory. In addition, the interference configurations of the MSIS system enable the measurement of coherence properties and phase information of nanophotonic materials, which is important for the study of light-matter interaction and beam shaping with nanostructures. The MSIS system can give the comprehensive information of nanophotonic materials, and is greatly useful for the study of novel photonic phenomena and the development of nanophotonic technologies.

关键词： Momentum space imaging Nanophotonic material Photonic dispersion Photonic eigenmode quality factor Polarization state

Modeling the performance of air filters for cleanrooms using lattice Boltzmann method

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Building Simulation 2021年第2期14卷 317-324页

作者： Bin Zhou Xiao Wu Long Chen Jia-Qi Fan Lan Zhu Department of HVAC College of Urban ConstructionNanjing Tech University211816NanjingChina National Air Cleaner&Gas Detect Production quality Supervision and Inspection Center(Jiangsu) SuzhouChina

Air filters with a low resistance,high filtration efficiency,and long lifetime are important to ensure good indoor air *** this study,the lattice Boltzmann method is applied on six types of fibrous filter media with lognormal-distribution models,which consider the influence of the solid fraction,number of fibers,and average fiber *** influences of the filtration velocity and fiber layout on the resistance,efficiency,and quality factor are *** resistance is found to be relatively low when the solid fraction inside the filter media is uniformly *** filter media with a random lognormal-distribution model demonstrated the best filtration performance in terms of quality ***,when the solid fraction is uniform along the thickness of the filter media,the comprehensive filtration performance is the best when a small fiber is near the inlet and a large one is close to the *** study provides a viable numerical method for performance optimization of air-filtration devices for the next-generation cleanroom industry.

关键词： LBM resistance filtration efficiency numerical simulation quality factor

Design of a photonic crystal microcavity for biosensing

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Journal of Semiconductors 2011年第3期32卷 75-80页

作者：李俊华阚强王春霞苏保青解意洋陈弘达 State Key Laboratory Integrated Optoelectronics Institute of SemiconductorsChinese Academy of Sciences

We have designed an air-bridged PhC microcavity with high sensitivity and a high quality *** structure parameters of the microcavity are optimized by three-dimensional finite-difference time-domain method. We compare the performance of a silicon-on-insulator PhC microcavity and an air-bridged PhC microcavity,and analyze the effect of the thickness of the slab and the radius of the defect hole on the performance of the air-bridged PhC *** a thinner slab and a larger defect hole,the sensitivity is higher while the quality factor is *** the air-bridged photonic crystal slab,the sensitivity can reach 320-nm/RIU（refractive index unit） while the quality factor keeps a relatively high value of 120 by selecting the proper slab thickness and the defect hole radius,respectively,when the refractive index is *** is meaningful for low-detection-limit biosensing.

关键词： air-bridged PhC microcavity biosensing sensitivity quality factor defect mode

Experimental analysis of an MIM capacitor with a concave shield

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Journal of Semiconductors 2009年第10期30卷 55-58页

作者：刘林涛喻明艳王进祥 Microelectronic Center Harbin Institute of Technology

A novel shielding scheme is developed by inserting a concave shield between a metal–insulator–metal （MIM）capacitor and the silicon *** measurements reveal that the concave shield improves the quality factor by 11%at 11.8 GHz and 14%at 18.8 GHz compared with an unshielded MIM *** also alleviates the effect on shunt capacitance between the bottom plate of the MIM capacitor and the shield ***,because the concave shields simplify substrate modeling,a simple circuit model of the MIM capacitor with concave shield is presented for radio frequency applications.

关键词： MIM capacitor concave shield quality factor model

A Graphene-Based Passively Q-Switched Ho：YAG Laser

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Chinese Physics Letters 2014年第7期31卷 99-102页

作者：姚宝权崔铮段小明申英杰王吉杜艳秋 National Key Laboratory of Tunable Laser Technology Harbin Institute of Technology Harbin 150001

A 2.09-μm in-band pumped passively Q-switched Ho： YAG laser is demonstrated. Single layer graphene deposited on a quartz substrate is used as the saturable absorber for the Q-switched operation. The minimum pulse width of 2.11μs is obtained at an average output power of lOOmW, corresponding to a pulse repetition frequency of 57.1 kHz and the pulse energy of 1.75 μJ. The beam quality factors M^2 of the Q-switched laser are 1.18 and 1.22 in the horizontal and longitudinal direction, respectively. The optical-to-optical conversion efficiency of the passively Q-switched laser is 4.3%, which is the highest conversion efficiency in the 2 μm wavelength, to the best of our knowledge. It shows clearly that the Ho： YAG crystal is a potential gain medium in the 2 μm range for the graphene application.

关键词： GRAPHENE Q-switched lasers HOLMIUM QUARTZ WAVELENGTHS quality factor

High-Efficient Nd：YLF Q-Switched Laser Operating at 523.5 nm

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Chinese Physics Letters 2014年第7期31卷 113-116页

作者：陆婷婷马剑黄敏捷杨琦朱小磊陈卫标 Key Laboratory of Space Laser Communication and Detection Technology Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800

An intracavity frequency doubling electro-optically Q-switched Nd： YLF 523.5 nm laser is developed. An appropriate cylindrical lens is employed in the oscillator to optimize the mode size and to improve the stability of the cavity. With an incident pump pulse energy of 58 mJ at a 500 Hz repetition rate, a green pulse energy of 16.8 mJ at 523.5 nm is obtained, corresponding to an optical-optical conversion efficiency of 29%. The pulse width is less than 8 ns, and the beam quality factor is M^2≤ 2.5.

关键词： NEODYMIUM lasers ELECTRO-optical effects quality factor LASER pulsed pumping LASERS -- Stability

Modified Photoluminescence by Silicon-Based One-Dimensional Photonic Crystal Microcavities

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Chinese Physics Letters 2005年第1期22卷 230-232页

作者：陈三钱波魏俊伟陈坤基徐骏李伟黄信凡 NationalLaboratoryofSolidStateMicrostructuresandDepartmentofPhysics NanjingUniversityNanjing210093

Photoluminescence (PL) from one-dimensional photonic band structures is investigated. The doped photonic crystal with microcavities are fabricated by using alternating hydrogenated amorphous silicon nitride (a-SiNx:H/a-SiNy:H) layers in a plasma enhanced chemical vapour deposition (PECVD) chamber. It is observed that microcavities strongly modify the PL spectra from active hydrogenated amorphous silicon nitride (a-SiNz:H) thin film. By comparison, the wide emission band width 208 nm is strongly narrowed to 11 nm, and the resonant enhancement of the peak PL intensity is about two orders of magnitude with respect to the emission of the lambda/2-thick layer of a-SiNz:H. A linewidth of Deltalambda = 11 nm and a quality factor of Q = 69 are achieved in our one-dimensional a-SiNz photonic crystal microcavities. Measurements of transmittance spectra of the as-grown samples show that the transmittance resonant peak of a cavity mode at 710nm is introduced into the band gap of one-dimensional photonic crystal distributed Bragg reflector (DBR), which further verifies the microcavity effects.

关键词： EMISSION Band gap emission TRANSMISSION SPECTROSCOPY Hydrogenated amorphous silicon Plasma enhanced chemical vapor deposition PNLIP gene quality factor pickling line microcavities crystals CSH1 gene photonic