实用高温超导混频器3mm锁相稳频源

基于小型脉冲管制冷机,设计并改善了与其配套的锁相混频系统,用约瑟夫森颗粒边界结实现了高温超导3mm波段96次谐波混频,完成了60次谐波下压控振荡器的锁相稳频实验.首次实现了基于小型脉冲管制冷机的实用高温超导混频器3mm锁相稳频源.     

一种新型的用于差分吸收激光雷达中脉冲式光学参量振荡器的种子激光器的频率稳定方法

提出了一种新型的用于差分吸收激光雷达中脉冲式光学参量振荡器的种子激光器的频率稳定方法. 详细介绍了该稳频方法的工作原理和实验装置, 并在理论上对该方法的稳频精度及其影响因素进行了分析. 利用该方法, 在实验中将种子光激光器稳定在水汽的吸收峰中心(935.6849 nm)处, 频率抖动的标准差小于8 MHz. 测试了种子注入后的光学参量振荡器输出的脉冲光的频率抖动, 测试结果表明, 脉冲光频率能够与种子光保持一致, 频率抖动的标准差小于28.7 MHz, 该稳频结果完全能够满足差分吸收激光雷达的需求.     

ESR波谱仪微波固体源的研制和测定电子自旋-晶格弛豫时间的简便方法

为了满足连续波饱和法测量顺磁场物质的电子自旋-晶格弛豫时间T₁对ESR波谱仪微波源的要求,制作了大功率、高稳定度的频带反射式外腔稳频耿氏振荡器,代替ESR波谱仪中较低功率的速调管源。     

X波段介质稳频压控振荡器的设计

介绍了X波段介质谐振器稳频、变容管调谐的微波集成场效应晶体管振荡器,叙述了利用介质谐振器的传输模设计反馈式振荡器以及对振荡器进行电调谐的设计思路,给出了测试结果。     

基于回音壁模式微球腔的PDH稳频技术

光学微球腔因其回音壁模式可获得极高的品质因数而受到广泛关注.本文分析了Fabry-Perot腔和微球腔的基本原理,通过CO2激光熔融光纤实验制得了直径为1.2 mm的微球腔,并测试了微球腔和锥形光纤耦合结构的耦合特性.采用典型的PDH稳频系统设计了基于微球腔的稳频系统,分析了用于鉴频的误差曲线的吸收特性和色散特性,对比了不同调制频率、微球腔直径、耦合损耗、传输损耗下与误差曲线斜率的关系.结果表明:耦合状态下最大Q值可达到1.1×108,调节微球腔内横磁模和横电模的转换可优化耦合效率,匹配微球腔和锥形光纤的尺寸得到了径向二阶模式的透射谱,误差曲线效率达到15.4A mW/MHz.球腔在提高PDH稳频技术灵敏度上具有巨大潜力.     

基于回音壁模式微球腔的PDH稳频技术（英文）

光学微球腔因其回音壁模式可获得极高的品质因数而受到广泛关注.本文分析了Fabry-Perot腔和微球腔的基本原理,通过CO2激光熔融光纤实验制得了直径为1.2mm的微球腔,并测试了微球腔和锥形光纤耦合结构的耦合特性.采用典型的PDH稳频系统设计了基于微球腔的稳频系统,分析了用于鉴频的误差曲线的吸收特性和色散特性,对比了不同调制频率、微球腔直径、耦合损耗、传输损耗下与误差曲线斜率的关系.结果表明:耦合状态下最大Q值可达到1.1×108,调节微球腔内横磁模和横电模的转换可优化耦合效率,匹配微球腔和锥形光纤的尺寸得到了径向二阶模式的透射谱,误差曲线效率达到15.4A mW/MHz.球腔在提高PDH稳频技术灵敏度上具有巨大潜力.     

高温超导混频器在锁相稳频源中的应用

基于小型脉冲管制冷机,设计并改善了与其配套的锁相混频系统,用约瑟夫森颗粒边界结实现了高温超导3mm波段96次谐波混频,完成了60次谐波下压控振荡器的锁相稳频实验。首次实现了基于小型脉冲管制冷机的实用高温超导混频器3mm锁相稳频源。     

异面腔四频差动激光陀螺的小抖动稳频

为了解决光强差稳频系统易受光电元件参量影响的问题,设计了一套用于异面腔四频差动激光陀螺的小抖动稳频系统。采用高频放大和幅度检波电路检出四频差动激光陀螺顺时针(或逆时针)输出光束的拍频幅度,然后用模数转换器采集到数字信号处理器(DSP)内。四频差动激光陀螺正常工作时拍频幅度取极大值,因此可通过对腔长进行小抖动调制实现稳频。利用DSP设计了一套数字式稳频系统,1 s取样的稳频精度为2×10-9,更重要的是稳频点不受光电元件参量变化的影响。设计的小抖动稳频电路精度高、通用性好,对提高四频差动激光陀螺适应恶劣环境的能力有一定的价值。     

激光锁频实验研究

随着激光技术的发展,激光的频率稳定性越来越好,实际应用对激光频率稳定性的要求也逐渐提高.目前简单的被动稳频技术已不能满足实际应用需求,而主动锁频技术备受关注并得到高速发展.更高的频率稳定度意味着需要更精确的调控,激光锁频技术也成为现代量子技术的重要组成部分.本文介绍了几种常用的激光稳频技术,展现了激光锁频技术的重要发展,例如小型化和自动化、超稳腔锁频和传输腔锁频.     

激光稳频技术的新发展(Ⅲ)──脉冲激光器的稳频技术和激光波长测量

脉冲激光器的频率稳定和测量,一向是一个较棘手的问题.但近年来,随着脉冲激光器在激光化学、激光光谱、激光雷达和外差检测系统等方面应用的发展,迫使人们去探索稳定脉冲光频的方法.下面介绍的几种脉冲激光稳频方法. 一、长期稳腔式[1]; 稳腔长当然可以稳定光频,但脉冲的持续时间短,较难判断腔长是否已被稳定,故采用一种长期稳腔的方案.这个方案在TEA CO2激光器中得到较合理实施,系统如图1所示,将TEA激光头和连续CO2器件置于同一谐振腔内,以构成混合式TEA激光器,获得单纵模振荡.通过连续器件的光电流稳频系统,以某一谱线(P或R的某一支…     

Circular Groove Guide Coupled with High-Q Cavity

The structure of circular groove guide coupled with high-Q cavity is studied. As a new type of millimeter wave component, it can be used for wavemeter and highly stabilized circular groove guide oscillator. The design and analysis of the novel structure are given in this paper.     

有源环形谐振腔辅助滤波的单模光电振荡器

提出并验证了一种有源环形谐振腔辅助滤波的光电振荡器. 它利用有源环形谐振腔提供的高Q光学梳状频率响应特性, 对振荡器中的光信号模式进行选择, 能有效地提高输出信号的边模抑制比, 获得光电振荡器的单模输出. 理论上, 对光电振荡器的起振模式以及有源腔的频率响应进行了分析, 仿真结果表明有源环形谐振腔的辅助滤波有利于光电振荡器的边模抑制和单模输出. 在实验上, 通过对比验证了理论的预期结果, 并最终得到中心频率为20 GHz, 边模抑制比为58.83 dB, 在频偏10 kHz处相位噪声为-97 dBc/Hz的单模信号输出. 该方案保留了已有光电振荡器边模抑制方法的优势, 实现方法上更加简便, 在工作带宽和可调谐性方面具备良好的灵活性.     

Injection locking of a diode laser locked to a Zeeman frequency stabilized laser oscillator

We describe the design and performance of an injection-locked diode laser locked to a stabilized, single frequency, unmodulated diode laser. The master oscillator is a grating-tuned, external cavity diode laser which is stabilized on a Doppler free alkali metal resonance transition frequency via Zeeman locking. The master oscillator frequency is shifted by an acousto-optic modulator, which provides optical isolation of the master oscillator laser while tuning of the acousto-optic modulation frequency can also provide frequency offset tuning. The slave laser is a free running diode which is injection-locked by a small fraction of the frequency shifted master oscillator light. Good long- and short-time frequency stability are observed for both the Zeeman-locked master oscillator and the injection-locked slave laser.     

Theoretical Study of Millimeter Wave Harmonic Oscillator Stabilized with a Transmission Cavity

An equivalent circuit model of millimeter wave second harmonic oscillator stabilized with a transmission cavity has been proposed for constructing analytical formulations between performance parameters of the oscillator and parameters of the circuit. The model consists of an equivalent circuit of fundamental wave and that of second harmonic wave. Each of the circuits comprises circuit models of main cavity, transmission waveguide, and transmission cavity. Absorbing material placed between the transmission waveguide and the transmission cavity can suppress additional resonances originated from transmission cavity. The behavior of the second harmonic oscillator can be effectively described by the circuit model. Furthermore, based on this model, mechanical tuning characteristics have been studied at first, and then analytical formulas for quality factor and efficiency depending on circuit parameters have been derived. The circuit parameters can be conveniently extracted by electromagnetic field simulation. Hence the formulas exhibit both compact form and enough accuracy. Thereafter, general rules of performance parameters varying with circuit parameters have been deduced for the harmonic oscillators. Then some design considerations have been derived according to the corresponding analysis. The equivalent circuit model is useful for designing and adjusting millimeter wave second harmonic stabilizing oscillator with a transmission cavity.     

500 GHz mode-hop-free idler tuning range with a frequency-stabilized singly resonant optical parametric oscillator

A 1064 nm pumped continuous-wave, mid-IR (3-4 μm), signal-wave resonant optical parametric oscillator is frequency stabilized at the kilohertz jitter level to the transmission peak of an external high-finesse Fabry-Perot cavity. Owing to the high stability of the resonator length against acoustical perturbation, fine pump tuning of the idler wave around 3.3 μm results in an unprecedented mode-hop-free continuous scan over 500 GHz (17 cm?1).     

A 37 mJ, 100 Hz,high energy single frequency oscillator

Ways on energy enhancement for single frequency oscillator are reported in this paper. By quantitative analysis on gain and loss coefficients for each cavity mode with inserted etalons, a 37 mJ, 100 Hz high energy single-frequency Nd:YAG oscillator is obtained. The pulse energy is promoted by enhancement of nearly 7 times for a single frequency oscillator reported. The result proves that this method does help for energy enhancement. It has attractive potential for high energy single frequency oscillator design, especially on condition of intensive side pumped or long cavity laser, where strong competitors exist and are hard to be suppressed.     

Low phase noise diode laser oscillator for 1S-2S spectroscopy in atomic hydrogen

We report on a low-noise diode laser oscillator at 972?nm actively stabilized to an ultrastable vibrationally and thermally compensated reference cavity. To increase the fraction of laser power in the carrier we designed a 20?cm long external cavity diode laser with an intracavity electro-optical modulator. The fractional power in the carrier reaches 99.9%, which corresponds to an rms phase noise of φ(rms)2=1?mrad2 in 10?MHz bandwidth. Using this oscillator, we recorded 1S-2S spectra in atomic hydrogen and have not observed any significant loss of the excitation efficiency due to phase noise multiplication in the three consecutive two-photon processes.     

Stabilized diode laser pumped, idler-resonant cw optical parametric oscillator

We present a diode laser pumped continuous wave, pump-enhanced singly-resonant optical parametric oscillator (OPO). The cavity is stabilized by a Pound?CDrever?CHall scheme using direct modulation of the diode laser. The system provides stable signal powers of up to 220?mW. The wavelength can be tuned between 1.40?C1.60???m for a ring or a linear cavity design by changing the crystal temperature. The relative fluctuations of the stabilized OPO??s wavelength are less than 10^?7 for more than one hour. Using a self-heterodyne technique, we measure a linewidth of the signal wave of 3.5?MHz.     

Ultra-stable microwave generation with a diode-pumped solid-state laser in the 1.5-μm range

We demonstrate the first ultra-stable microwave generation based on a 1.5-μm diode-pumped solid-state laser (DPSSL) frequency comb. Our system relies on optical-to-microwave frequency division from a planar-waveguide external cavity laser referenced to an ultra-stable Fabry–Perot cavity. The evaluation of the microwave signal at ~10 GHz uses the transportable ultra-low-instability signal source ULISS^®, which employs a cryo-cooled sapphire oscillator. With the DPSSL comb, we measured ?125 dBc/Hz phase noise at 1 kHz offset frequency, likely limited by the photo-detection shot-noise or by the noise floor of the reference cryo-cooled sapphire oscillator. For comparison, we also generated low-noise microwave using a commercial Er:fiber comb stabilized in similar conditions and observed >20 dB lower phase noise in the microwave generated from the DPSSL comb. Our results confirm the high potential of the DPSSL technology for low-noise comb applications.     

Mode-locked Yb:KGW laser longitudinally pumped by polarization-coupled diode bars

Mode-locked operation of a simple Yb:KGW (potassium gadolinium tungstate) oscillator is described, providing 10 W at 1039 nm with a 290 fs pulse width. A polarization-coupled scheme is used for efficient longitudinal pumping by a pair of reshaped laser diode bars. With changes in cavity dispersion, the pulse width is adjustable from 134 to 433 fs, in a high-quality circular mode. A saturable absorber mirror provides self-starting operation, and the cavity is stabilized by the Kerr-lens effect.