串联双微环谐振腔系统的相干特性研究

为研究硅基光波导中耦合诱导透明和光学Fano共振效应,设计并加工了一种串联双环谐振腔结构。通过高温退火表面光滑化处理,使得波导粗糙度降低为0.545 nm,实验中利用垂直光栅耦合法对结构进行测试,测试结果表明:当两环半径相等时,由于相消干涉,产生CRIT效应;当两环半径不相等时,产生谐振分离现象。同时与传统的单环谐振腔结构相比,串联双环谐振腔结构半高全宽(FWHM)增强了3倍,并且降落端口消光比增加了20 dB。     

光纤光梳温度反馈控制方法研究

为了解决光学频率梳长时锁定困难的问题,对光学频率梳重复频率（fr）与载波相位偏移频率（f0）的控制方法进行了改进。采用上、下两块半导体制冷片（TEC）对振荡器局部环境进行温度控制,并微调TEC温度将fr与f0漂移量分别稳定在10 Hz和600 Hz以内。利用锁相电路反馈控制有效腔长和泵浦光功率对fr与f0进行了精密锁定...     

基于透射式非稳腔的单纵模TEA CO_2激光器

为了获得TEA CO_2激光器高质量的单纵模输出,对种子注入锁定的TEA CO_2激光器进行了研究。首先,本文提出了一种透射耦合输出的虚共焦非稳谐振腔方案,利用Glad软件的Prony法对腔模的演化进行了仿真分析,并实验记录了近场与远场的光斑光强分布。仿真结果与实验结果吻合,验证了此腔型方案的合理性。其次,在此腔型的基础上进行了腔外种子注入锁定实验,实验结果显示:自由振荡时存在频率为195 MHz的拍信号,当种子注入锁定成功后,输出激光拍频消失,波形变光滑,峰值功率降低48.6%,脉冲产生时间缩短20ns。实验结果与已有成果吻合,验证了此种透射式非稳腔的TEA CO_2激光器具有输出高质量单纵模的能力。     

《地基光电望远镜技术》专题文章导读：光电跟踪伺服系统的频率特性测试与模型辨识

基于光电跟踪伺服系统全数宁化的特点．提出了一种新型频率特性测试方法．并对该方法所使用的激励信号、数据采集方式、幅值和相位提取算法、模型辨识算法进行了研究。利用数字运动控制器产生离散的正弦扫频信号,同时采集响应信号并存储在磁盘上,对其进行测试后．将文件导入Matlab进行数据预处理;然后,采用桐关分析方法计算输入输出信号的幅度比和相位差;最后,利用递阶辨识算法将测量得到的数据转化为高精度的传递函数。实验结果表明,测试信号基本可以覆盖伺服控制系统的频带宽度,在系统的中频段可以获得幅度±0．5dB和相位±1°的辨识精度,在高频段也可以使用双二节滤波器拟合出机械谐振频率,证明了该方法的有效性和实用性。     

随机振动下光学谐振腔腔体形变及变动规律

鉴于复杂环境会使激光陀螺谐振腔产生变形,从而严重影响激光陀螺的性能,本文利用有限元分析软件ANSYS仿真分析了典型随机振动谱(gRMS=6.6 g)下激光陀螺腔镜3个方向的微小形变量,分别为0.342 5″、0.349 4″和0.215 0″,并结合矩阵光学理论定量得到了谐振腔光阑处的形变量。然后定量分析了不同曲率半径、不同腔长、不同入射角对光学四边形环形谐振腔的影响规律。最后,研究了球面镜-球面镜同时变化以及球面镜-平面镜同时变化下谐振光路的变动规律。实验结果表明,单纯考虑谐振腔的抗振性能,当L处于0~1m,R处于1~8m时,球面镜的曲率半径越小,腔长越短,四边形环形光学谐振腔所受外界环境的影响越小,两个腔镜同时变化时按照一定规律等效成单镜变化。本文研究可以为激光陀螺光学谐振腔的设计提供参考。     

两路脉冲固体激光器的相干合成

提出了采用迈克尔逊干涉复合腔技术进行两路固体激光器相干合成的实验方案.该方案利用双光束干涉时的相干相长和相干相消特性,结合谐振腔自身的增益损耗原理来实现两激光器的被动式相干合成.理论分析了该技术的锁相机理,并在实验中实现了两路脉冲固体激光器的相位锁定,获得了单脉冲能量300 mJ的相干合成激光输出,合束效率约为80％....     

基于谐振腔理论的加速度传感器设计

为了实现新型的可集成微纳加速度传感器,文中采用微纳光纤设计了环形谐振腔的加速度传感器。通过电场的传数矩阵推导了谐振腔中的速度变化与光强变化间的关系,得到了加速度作用下微环谐振腔的谐振波长、周长、有效折射率的变化值间的函数关系。结果表明:设计的微环波导电场波动明显,耦合效率较好;光谱强度和3 d B带宽变化较小,Q值达到105;在质量块每增加10 g时,输出光谱图约向右漂移3 nm;加速度与谐振波长漂移量基本成线性关系,可以通过谐振波长的漂移量来实现对加速度的测量。     

谐振和调制在锁频技术中的应用研究

近年来,谐振及调制因其稳定度高、可操作性强等原因在激光器锁频技术中的应用越来越广泛。文章从谐振技术及调制技术两方面的共选取6种典型的激光器锁频实验系统进行综合分析,认为:通过控制谐振腔腔长的激光器锁频实验系统相对简单,选择好的腔体材料、设计好伺服控制电路就能实现快速锁定,其中双重锁定稳定度较高;通过加载调制的激光器锁频实验系统比较复杂,用到的实验仪器较多,内调制会对激光产生扰动,其中调制转移谱的锁频方法稳定度较高。为激光器锁频技术的优化提供参考。     

小型脉冲固体激光器输出特性的实验研究

为考察输入能量、输出镜透过率、谐振腔腔长、调Q方式等因素对小型脉冲固体Nd∶YAG 激光器输出能量的影响,进行了实验研究.结果表明输入能量是影响输出能量的最大因素;当输入能量一定时,存在最佳腔长与最佳输出镜透过率;采用Cr∶YAG晶体调Q后的输出能量始终高于采用BDN染料片调Q后的输出能量.     

F-P光纤传感器的损耗特性分析及其研制

对反射型非本征F-P干涉型(Extrinsic Fabry-Perot Interferometer,EFPI)光纤传感器的损耗特性进行了分析,表明当腔长小于100μm时,随着腔的变长光能量耦合损耗迅速增加;在考虑腔损耗的情况下,分析了如何合理选择两反射面的反射率以使输出光强的对比度达到最大;通过分析在制作F-P腔的过程中影响腔长变化的原因,总结出了一个可以准确控制和调整腔长的方法;依以上规则制作了F-P光纤传感器,并进行了实验验证。     

Influence of the cavity parameters on the output intensity in incoherent broadband cavity-enhanced absorption spectroscopy

The incoherent broadband cavity-enhanced absorption spectroscopy is a technique in measuring small absorptions over a broad wavelength range. The setup consists of a conventional absorption spectrometer using an incoherent lamp and a charge coupled device detector, as well as a linear optical cavity placed around the absorbing sample, which enhances the effective path length through the sample. In this work the consequences of cavity length, mirror curvature, reflectivity, different light injection geometries, and spot size of the light source on the output intensity are studied and the implications to the signal-to-noise ratio of the absorption measurement are discussed. The symmetric confocal resonator configuration is identified as a special case with optimum imaging characteristics but with higher requirements for mechanical stability. Larger spot sizes of the light source were found to be favorable in order to reduce the negative effects of aberrations on the intensity.     

A microtron cavity with a shifted cathode for operation in the second-type acceleration mode

The motion of electrons in a microtron with the second-type acceleration mode is calculated and an optimum location of the emitter in the cavity resonator is found, which permitted us to increase the current capture efficiency. The testing technique and test results for a 20-orbit microtron with such a cavity are described. For an electron output energy of 18 MeV, the current capture efficiency was ∼9%.     

An oscillator with low phase noise based on active resonator using metamaterial in K-band

An oscillator(OSC)with a metamaterial resonator based on high-Q is designed to improve the phase noise in Kband.The proposed metamaterial resonator is a lattice structure resonator(LSR)that is designed to be high-Q by a strong coupling of E-field at the resonance frequency.Thus the output of OSC is about 12.5dBm at the f0.The phase noise is 109.477dBc/Hz at 100kHz offset frequency.     

Nano force sensing using symmetric double stage micro resonator

A new approach is proposed to improve a graphical approach with considering intensity coupling loss coefficients in the analytical derivation of the optical transfer functions for a symmetric double stage vertically coupled microring resonator. An optimum transmission coupling condition is determined with considering terms of couplers intensity loss which leads to low insertion loss of 1.2 dB, finesse of 1525, the out of band rejection ratio of 61.8 dB. The resonating system is used as an optical force sensing system to make the benefit of the accuracy of measurements in micro and nano scales. The sensitivity of proposed force sensor in terms of wavelength-shift is 33 nm/nN and the limit of detection is 1.6 × 10⁻² nN. The proposed sensing system has the advantages of self-calibration and the low power consumption due to the low intensity.     

Note: Coherent detection of terahertz radiation employing a continuous wave optical parametric source

The combination of an all-optical terahertz source with a photoconductive antenna to achieve coherent detection is presented. This approach aims to overcome the frequency limits introduced by optoelectronic terahertz sources commonly used. Here the Gaussian-shaped and linearly polarized terahertz waves are generated by a continuous wave optical parametric oscillator with a power of 3 μW at 1.4 THz. The infrared signal light of the optical parametric oscillator can be used to coherently detect the generated terahertz wave with a photoconductive antenna. As a proof-of-principle experiment we determine the thickness profile of a plastic lens using phase shifting interferometry.     

A low-noise microwave signal source

An ultrafast electron diffraction setup is described and requirements for a signal source are determined. Taking into account these requirements, a low-noise microwave signal source with a 6.2-GHz-frequency and ≥6-W power, and 6.1-GHz additional frequency and ≥5-mW power is designed. The phase noise level at the output frequency was no higher than −115 dB/Hz when the offset from the carrier was 10 kHz. The manufactured setup was supplied to the Max-Planck Institute (Garching, Germany), experiments were performed, and the first results were obtained.     

太赫兹可调谐滤波器设计

为了实现太赫兹信号的可调谐滤波,设计了一种基于柔性材料的太赫兹可调谐滤波器。通过扭曲特氟龙（Teflon）波导形成环型谐振器,实现了160～200 GHz频段的带阻滤波功能。改变谐振腔长可实现自由频谱范围（FSR）和滤波频点的调谐,实验测试了自由频谱范围在1.9 GHz和2.8 GHz间切换以及相应的滤波特性。研究表明,谐振腔长一定时,改变弯曲半径可实现滤波阻带抑制度的调节,柔性材料太赫兹环型谐振器可用于可调谐滤波,且具有较高的自由度。     

重复频率锁定的783 nm飞秒光纤激光器研制

设计并搭建了重复频率长时精确锁定的783 nm飞秒光纤激光器。该激光器基于全保偏非线性干涉环镜(NALM),实现掺铒光纤振荡器锁模脉冲输出,由与脉冲分离器级联的环境稳定掺铒光纤双级放大器进行功率放大,实现了平均功率1.30 W、脉冲宽度130 fs、重复频率77.1 MHz、1 560 nm脉冲输出;通过周期极化铌酸锂(PPLN)光学晶体倍频,获得了平均功率为0.52 W、脉冲宽度为140 fs、783 nm脉冲输出。通过重复频率监测及锁相环技术,进一步将掺铒光纤振荡器的重复频率溯源至参考铷原子钟,12 h内频率抖动峰-峰值为5 mHz、标准偏差为1.2 mHz。该激光器系统具有稳定性高、集成度高、体积小的特点。     

Beam current enhancement of microwave plasma ion source utilizing double-port rectangular cavity resonator

Microwave plasma ion source with rectangular cavity resonator has been examined to improve ion beam current by changing wave launcher type from single-port to double-port. The cavity resonators with double-port and single-port wave launchers are designed to get resonance effect at TE-103 mode and TE-102 mode, respectively. In order to confirm that the cavities are acting as resonator, the microwave power for breakdown is measured and compared with the E-field strength estimated from the HFSS (High Frequency Structure Simulator) simulation. Langmuir probe measurements show that double-port cavity enhances central density of plasma ion source by modifying non-uniform plasma density profile of the single-port cavity. Correspondingly, beam current from the plasma ion source utilizing the double-port resonator is measured to be higher than that utilizing single-port resonator. Moreover, the enhancement in plasma density and ion beam current utilizing the double-port resonator is more pronounced as higher microwave power applied to the plasma ion source. Therefore, the rectangular cavity resonator utilizing the double-port is expected to enhance the performance of plasma ion source in terms of ion beam extraction.