Bandwidth,sharpness, and visibility of resonances in light reflectance and transmittance of free monolayer Fabry-Perot interferometers

The conditions for the formation of Fabry-Perot resonances in optical reflectance and transmittance spectra by transparent and absorbing interferometers are investigated. Relations describing their instrumental characteristics are derived.     

基于超材料角反射面的高增益高效率双圆极化Fabry-Perot天线设计

基于射线跟踪模型,提出了一种超材料角反射面结构,实现了Fabry-Perot天线增益和口径效率的提升.首先对基于超材料角反射面的Fabry-Perot天线进行了理论推导和分析.然后,设计并分析了双圆极化馈源、基于超材料角反射面的Fabry-Perot天线及其性能.最后,对所提出的Fabry-Perot天线模型进行了制造和测试.结果表明,该天线的左圆极化增益和右圆极化增益分别为21.4 d Bi和21.3 d Bi.相比馈源天线,增益分别提高了16.4 d B和16.3 d B.与传统Fabry-Perot天线相比,所提出超材料角反射面同时充当了反射面和相位校正面,实现了对Fabry-Perot天线边缘电磁波的有效调控.所设计Fabry-Perot天线工作在2.8 GHz频段,具有高增益、高口径效率和低旁瓣的优点,满足了太阳射电望远镜F107指数观测的需求.     

Effect of frequency chirping of light from a Q-switched ruby laser on the speckle in Fabry-Perot rings

It has been observed that, when a Fabry-Perot interferometer was illuminated through a diffuser with light from a Q-switched ruby laser, the speckle smeared out in the Fabry-Perot rings. This is interpreted as a movement of the individual speckle resulting from the frequency chirping of light from the ruby laser and the high resolution of the Fabry-Perot interferometer.     

光纤法布里-珀罗传感器串连复用的傅里叶变换解调方法初探

光纤法布里—珀罗传感器复用、特别是串连复用的解调十分困难。为解决这个问题,从光纤法布里—珀罗应变传感器的基本原理出发、在仅有两只传感器复用的基本条件下,深人分析了复用系统组合输出光强信号及其分布特性;研究了对其进行傅里叶变换的解调原理及具体实现方法,分析了因复用信号不满足傅里叶变换条件而在变换域产生的畸变,进行了计算机仿真解调。在此基础上,搭建了两只传感器的串连复用实验系统,并用此方法实现了两只复用传感器的解调,且传感器之间的相互影响小于5％。理论与实验表明,虽然传感器的复用信号不满足傅里叶变换的标准条件,且仿真与实验存在一定差异,但所提出的傅里叶变换方法,基本可用于光纤法布里—珀罗传感器的串连复用解调。     

F-P半导体激光器实现多波长注入锁定

F-P半导体激光器中对于TE模比TM模有更大的束缚系数,并且在其反射面上有更高的反射率.当TE模和TM模同时注入F-P半导体激光器的谐振腔时,TE模方向的信号得到增长,TM模方向的信号受到抑制.F-P半导体激光器的这种特性使得它类似于一个偏振器,但是其优越之处在于经过F-P半导体激光器注入锁定之后的光信号没有功率损耗.采用F-P半导体激光器的注入锁定原理,使入射光信号没有功率损耗地由偏振光转换为部分偏振光,降低了通信系统中传输信号的偏振敏感性,使传输信号的质量得到提高,实现了F-P半导体激光器三波长和四波长注入锁定.     

The operation of THz quantum cascade laser in the region of negative differential resistance

We investigate the light-current-voltage characteristics and emission spectra of 2.3 THz quantum cascade laser operating in the negative differential resistance (NDR) region. It was shown that the formation of electric field domains (EFDs) leads to a large number of discontinuities on the current-voltage and the total optical power on current characteristics. Measurements of emission spectra at different current (before the NDR region and in the NDR region) shows that the formation of EFDs results in decrease of the output intensity, but does not influence on Fabry-Perot multi-mode structure of THz QCL. The developed theoretical model predicts the formation of EFDs in the NDR region and qualitatively explain the experimental results.     

Holographic Fabry-Perot spectrometer

We propose a spectrum analyzer based on the properties of a hologram recorded with the field transmitted by a Fabry-Perot etalon. The spectral response of this holographic Fabry-Perot spectrometer (HFPS) is analytically investigated in the paraxial approximation and compared with a conventional Fabry-Perot etalon of similar characteristics. We demonstrate that the resolving power is twice increased and the free spectral range (FSR) is reduced to one-half. The proposed spectrometer could improve the operational performance of the etalon because it can exhibit high efficiency and it would be insensible to environmental conditions such as temperature and vibrations. Our analysis also extends to another variant of the HFPS based on holographic multiplexing of the transmitted field of a Fabry-Perot etalon. This device increases the FSR, keeping the same HFPS performance.     

Transmitting intensity distribution after a Gaussian beam incidenting nonnormally on a wedged Fabry-Perot cavity

After deriving the expression of the intensity of the transmitted beam for a Gaussian beam nonnormally passing through a wedged Fabry-Perot cavity, the influence of the wedged angle in Fabry-Perot cavity mirrors alignment at a different tilted angle on the transmission of a Gaussian beam has been investigated theoretically. Numerical simulations show that the incidental angle and the wedged angle in Fabry-Perot cavity mirrors alignment have an important effect on the intensity distribution, the peak intensity, and the position of the peak intensity of the transmitted beam.     

Generation of Raman polaritons in three-level atomic media

A theory of formation of Stokes field (Raman) polaritons, which arise due to the coherent stimulated Raman scattering of light in an ensemble of three-level atoms placed in a Fabry-Perot cavity in the case of a strong coupling regime, is developed. The dispersion and absorption properties of Raman polaritons are investigated and the conditions for polariton amplification are found. It is shown that for certain pump power values, nonclassical correlations (entanglement) between light and dark polaritons are observed in the system.     

Strain Sensor Using Optical Fiber Unsymmetrical F-P Cavity and the Characteristic Analysis

An intrinsic Fabry-Perot cavity consisted of different reflective mirrors is used in fiber-optical sensors for measuring the strain. The character of the unsymmetrical fiber-optical Fabry-Perot cavity and fiber-optic longitudinal stress-strain effect is analysed. The general theory and measurement method of strain are presented. A low fineness Fabry-Perot cavity is used to improve the linearity of optical fiber strain sensors. The result of experiment agrees well with the theory.     

基于有源Fabry-Perot腔的激光脉冲延时自外差研究

对注入有源Fabry-Perot腔内的单纵模脉冲进行了延时理论分析, 计算了Fabry-Perot腔内增益, 并对脉冲输出进行了数值模拟, 结果表明当脉冲能量衰减到一定值时, 新增抽运粒子数提供的增益可以补偿腔内损耗, 延时脉冲的输出可以达到稳态. 然后利用激光二极管侧面抽运Nd: YAG激光器做为Fabry-Perot腔, 对外部入射的单纵模脉冲光进行了延时, 得到了延时时间2 μups、脉冲数量140个的实验结果. 最后利用有源Fabry-Perot腔对参考光进行延时, 声光移频器对信号光产生频移, 进行了外差实验, 实验结果与移频器的设置值相符, 误差在4%以内.     

法-珀腔干涉仪的实验研究

在分析法-珀腔干涉仪测量原理的基础上,阐述了它在高分辨率光谱测量领域中的应用。搭建了一套法-珀腔干涉仪系统,利用该系统对某多纵模氦氖激光器的模式进行了实际测量,并就实验结果进行了分析。     

Harmonic and Intermodulation Performance of Fabry-Perot Intensity Modulator

Abstract

In this article, a mathematical model for the transfer function of the Fabry-Perot intensity modulator is presented. The model, basically a cosine-series function, can be used to obtain closed-form expressions for the amplitudes of the harmonic and intermodulation products of the Fabry-Perot intensity modulator driven by a multi-frequency radio frequency voltage. The special case of a Fabry-Perot intensity modulator driven by an equal-amplitude two-frequency radio frequency voltage is considered in detail, and the results are compared, whenever possible, with previously published experimental and numerically obtained results.     

Time-resolved spectral analysis of transient processes in Fabry-Perot interferometers

Parameters of a spectrochronograph that represents a Fabry-Perot interferometer combined with a spatial-time analyzer (a streak camera) are analyzed. Using numerical simulation, time scans of interferograms for bandwidth-limited and phase-modulated pulsed optical signals are obtained. The conditions are determined under which a Fabry-Perot interferometer represents a high-accuracy instrument for measuring the timeresolved spectral dynamics of short optical signals. In particular, an adequate representation of relatively smooth and monotone changes in amplitude and phase characteristics of an optical signal in a spectrochronograph requires that the mode lifetime in a Fabry-Perot interferometer be matched to the time scale of changes in the spectral structure of a pulse being studied. The character of distortions formed in the time-resolved spectral patterns in the case where these conditions are not fulfilled is qualitatively determined, and quantitative estimates of the distortions are presented. The results of the analysis and the numerical calculations show that a spectrochronogram obtained using a Fabry-Perot interferometer and a time analyzer (a streak camera) with parameters corresponding to the criteria formulated in the paper enable one to obtain information on the initial amplitude-phase pattern of a light pulse.     

Ultracompact resonant filters in photonic crystals

A novel design for an ultracompact, high-Q notch-rejection filter is presented, and an analytic expression for the transmission properties is derived. This folded directional coupler shares the properties of a Fabry-Perot resonator and a directional coupler. We compare and contrast the device to high-Q Fabry-Perot cavities in photonic crystal waveguides.     

A new method for angular displacement measurement

We describe a new method for angular displacement measurements that is based on a Fabry-Perot interferometer. A measurement accuracy of 10-8 rad is obtained by use of the sinusoidal phase modulating interferometry. Another Fabry-Perot interferometer is used to obtain the key initial angle of incidence.     

双边缘技术多普勒测风激光雷达标准具的优化

 优化了基于双边缘技术的直接测风多普勒激光雷达中F-P标准具的工作参数。确定激光谱宽后，选择适当的F-P标准具自由谱间距，可正确消除瑞利背景噪声的影响。分析了标准具镜面缺陷、非严格平行和入射光束发散角对其透过率曲线的影响。将标准具透过率函数表达为唯一系统参数，即反射精细度的函数；通过计算散粒噪声极限时的相对测量误差，可确定最优反射精细度以及激光频率相对标准具透过率中心频率的最佳偏置；由最优反射精细度可得到入射到标准具光束的最大发散角和标准具的最小通光口径。     

The interaction between single-mode laser radiation and sodium vapour in a Fabry-Perot etalon and a ring optical cavity

The observation of optical bistability in the D lines of sodium vapour contained in both a Fabry-Perot etalon and a ring cavity is reported. As well, an enhanced transmission feature which appears under appropriate conditions in the Fabry-Perot etalon only is presented. This feature is interpreted in terms of a non-absorption resonance in an inverted V three-level model of the sodium D transitions.     

Fiber Fabry-Perot Cavity Using Sagnac Loop with Phase-Shift Grating

Fiber Fabry-Perot cavity using Sagnac loop with phase-shift grating is investigated. Various interference patterns corresponding to the different fiber Fabry-Perot cavities are obtained, and their potential applications in multiwavelength fiber laser source are discussed.     

Fabry-Perot etalons as prefilters for astronomical far-infrared fourier transform spectroscopy

We show that a Fourier transform spectrometer (FTS) can be made competitive in sensitivity (system noise equivalent power) with scanning single detector spectrometers (SSDS) such as scanning Fabry-Perot spectrometers or grating instruments for work on specific lines in FIR astronomy by prefiltering the radiation so that the broadband background on the detector(s) of the FTS is reduced. Fabry-Perot etalons made with electroformed metal mesh reflectors are suitable prefilters. A Fabry-Perot prefiltered FTS has a capability for simultaneous observation of lines at substantially different wavelengths in the same beam on the sky. The lines are passed by different orders of the Fabry-Perot, and their separation and resolution is accomplished by the FTS. We discuss the sensitivity comparison between the prefiltered FTS and an SSDS, identify several suitable pairs of astrophysically interesting lines, discuss some of the technical aspects of building very compact etalons designed for use at LHe temperatures, report new measurements of properties of commercially available metal mesh, and describe the performance of etalons built for line pairs near 50 μm.