Author Affiliations
Abstract
Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
We experimentally investigated the forward 353.8 nm radiation from plasma filaments in pure nitrogen gas pumped by intense circularly polarized 800 nm femtosecond laser pulses. This emission line corresponds to the transition of nitrogen ions. In the presence of an external seeding pulse, the 353.8 nm signal was amplified by 3 orders of magnitude. Thanks to the much enhanced intensity, we performed time-resolved measurement of the amplified 353.8 nm emission based on the sum-frequency generation technique. It was revealed that the built-up time and duration of these emissions are both inversely proportional to the gas pressure, while the radiation peak power grows up nearly quadratically with pressure, indicating that the 353.8 nm radiation is of the nature of superradiance.
femtosecond pulses plasma nitrogen ions superradiance time-resolved measurement Chinese Optics Letters
2020, 18(2): 023201
中山大学光电材料与技术国家重点实验室, 广东 广州510275
半导体量子点的激子超辐射出现的条件是本文激子超辐射的理论研究中的重点，我们的理论推导结果揭示要观测到半导体量子点的激子超辐射必须采用短于百飞秒的激发源。我们用ZnO单量子点观察到激子超辐射，同时测量和分析讨论了量子点集合的相干辐射性质，发现单量子点超辐射的二次方泵浦与辐射强度关系被大量量子点间的线性递增所掩盖。
量子点 激子 超辐射 激射 半导体纳米晶集合 quantum dot exciton superradiance lasing nano-crystal assemble
中国工程物理研究院 应用电子学研究所,四川 绵阳 621900
运用超辐射机理,通过粒子模拟设计了X波段超辐射相对论返波管,并在小型Tesla脉冲源平台上开展了实验研究。通过空间功率积分和直接对辐射微波时域波形的分析得到实验结果:在束压350 kV、束流4.8 kA、脉宽3.1 ns、引导磁场2.2 T条件下,产生的微波辐射功率1.4 GW,中心频率9.36 GHz,脉宽500~700 ps,辐射模式为TE11,能在重复频率100 Hz下稳定运行。功率转换效率超过80%。实验结果与粒子模拟结果比较吻合,成功实现了在短脉冲条件下产生重复频率、亚纳秒脉宽、GW级微波辐射。
超辐射 相对论返波管 亚纳秒 高功率微波 superradiance relativistic backward wave oscillator subnanosecond high power microwave
对新型同轴单程超辐射相对论返波管振荡器进行了进一步的研究。该振荡器的互作用区为同轴结构,外导体为一波纹波导,内导体为一光滑圆波导;辐射场从左端耦合到圆波导后输出,不需要截止颈。通过增加波纹周期数并调整互作用区末端波纹深度,器件的功率转换效率得到进一步的提高。当电子束电压为360 kV,电流为9.15 kA,外加磁场强度为2.7 T时,通过参数优化,模拟获得了瞬时峰值功率超过18 GW、脉冲宽度约400 ps,中心频率为8.1 GHz的微波输出,平均功率转换效率达到了275%。
超辐射 相对论返波管振荡器 数值模拟 功率转换效率 superradiance relativistic backward wave oscillator numerical simulation power conversion efficiency
Author Affiliations
Abstract
Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
A high energy pulsed terahertz (THz) laser is studied experimentally. The laser cavity simply consists of a quartz glass waveguide, a coated GaAs input window, and a crystal quartz output window. NH3 is filled in the cavity as gain medium, and pumped by an 8-J line-tunable transversely excited atmospheric (TEA) CO2 laser. When 9R(16) transition acts as the pump line, 55.6-mJ THz radiation (90 \mu m) is obtained at 730-Pa NH3 pressure. The corresponding conversion efficiency is 13.54%. Energy and optimal pressure of amplified spontaneous emission and laser oscillation are compared.
太赫兹 TEA CO2激光器 NH3 140.3070 Infrared and far-infrared lasers 140.4130 Molecular gas lasers 140.6630 Superradiance, superfluorescence Chinese Optics Letters
2010, 8(4): 411
中国工程物理研究院 应用电子学研究所,四川 绵阳 621900
为开发回旋超辐射在毫米波和亚毫米波超辐射高功率微波源中的优势,采用3维PIC粒子模拟对回旋超辐射的工作特性进行了分析,并在此基础上优化设计了器件结构及工作参数范围。模拟表明,微波峰值功率与电子束脉宽在一定范围内成平方关系,符合超辐射的典型特征。初步实验在210 kV,250 A的电子束参数下获得了6 MW的微波峰值功率输出,工作频率37.2 GHz,模式为TE01,与粒子模拟的结果基本一致。
高功率微波 回旋超辐射 毫米波 粒子模拟 HPM cyclotron superradiance millimeter wave particle simulation
Author Affiliations
Abstract
1 Department of Physics, Xiamen University, Xiamen 361005, China
2 Department of Physics, Jimei University, Xiamen 361021, China
3 Department of Electronic Engineering, Xiamen University, Xiamen 361005, China
We investigate the characteristics of the dual-forward synchronously pumped L-band erbium-doped superfluorescent fiber source (SFS). The effects of pump ratio and fiber length arrangements on the output characteristics of the L-band SFS in terms of mean wavelength, spectral linewidth, and output power are analyzed. It is shown that the optimized pump ratio and fiber length arrangements provide broadening spectral linewidth and enhanced pumping efficiency, while the synchronous pump ensures stable mean wavelength operation. A new single-forward pumping scheme with a section of unpumped fiber is proposed to achieve a mean wavelength stable L-band SFS with a broadening linewidth of 50.4 nm and a pumping efficiency of 33.5%.
光纤放大器与振荡器 掺铒光纤 超荧光光源 放大自发辐射 060.2320 Fiber optics amplifiers and oscillators 060.2410 Fibers, erbium 140.6630 Superradiance, superfluorescence Chinese Optics Letters
2009, 7(7): 07568
提出了采用可调谐TEA CO2超辐射激光器对硼同位素分离的研究方法。反应室长20cm，内直径5cm，室内BCl3／O2混合物经聚焦单频超辐射激光脉冲照射350次，生成物(B2O3)中10B的富集系数达1．24，选择系数(关于10B)达1．29，证实了超辐射CO2激光具有选择性激发分离同位素和多光子离解分子的能力。
可调谐 TEA CO2超辐射激光器 分离同位素 tunable TEA CO2 superradiance laser separation of isotope
Author Affiliations
Abstract
1 National Laboratory on High Power Lasers and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
2 State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050
In this paper, the Yb-doped superfluorescent fiber source (SFS) with cascaded broad fiber Bragg gratings (FBGs) are reported. The spectral properties of this SFS with cascaded broad FBGs are described and compared with that without cascaded broad FBGs. The experimental results have shown that cascaded broad FBGs can increase the output of some special wave bands.
060.0060 fiber optics and optical communications 140.6630 superradiance superfluorescence 170.6280 spectroscopy fluorescence and luminescence 140.0140 lasers and laser optics Chinese Optics Letters
2003, 1(3): 03131
