微波电光调制BOTDR系统中参考光功率稳定控制

在基于微波电光调制的布里渊光时域反射分布式温度传感系统中,使用微波扫频会造成电光调制器输出的参考光功率波动,根据相干检测的原理,参考光功率的波动会影响到测得的后向布里渊散射信号的功率,将直接影响布里渊散射谱的测量精度,导致较大的温度测量误差。因此,提出一种根据电光调制器输出光功率反馈调节微波源功率,以稳定布里渊光时域反射系统参考光功率的方法。实验结果表明,该方法可以有效抑制电光调制器输出的一阶边波带峰值功率的波动,使系统的温度测量精度从6℃提高到了2℃。     

300MHz 衰减全反射型有机聚合物电光调制器

基于衰减全反射原理的反射型有机聚合物电光调制器,具有成本低、插入损耗低、受聚合物本征损耗影响小、工作波长范围宽等优点。本文采用了溅射,旋转涂覆,电晕极化等方法来制作电极,并通过减小衰减全反射型有机聚合物电光调制器上下两电极的重叠面积,提高了器件的调制带宽,在实验上实现了300MHz射频信号的调制。     

新研制的高精度动态光电显微镜

由中国计量科学研究院、昆明机床厂和云南省计量测试研究所共同研制的高精度动态光电显微镜,于1983年12月21日在昆明通过国家鉴定。 本仪器采用氟-氖激光器作光源,由电光调制器对激光束进行调制。通过柱面镜和沿光轴方向移动的渥拉斯通棱镜获得间距可调的二个光斑,并用一个光电倍增管同时接收此两光     

多载波输入时星间微波光子链路性能分析

针对卫星通信中射频载波信号光学传输问题,建立了星间微波光子链路,利用两个并联双电极马赫-曾德尔电光调制器,以光载波抑制调制方式实现了星间微波信号的光域传输和下变频。利用贝赛尔函数展开推导了多载波输入情况下接收信号任意谐波和交调分量表达式,得到了输出信号噪声失真比与输入载波数关系,利用曲面投影法求得了不同载波数时电光调制器最佳调制系数,分析了载波数对最佳调制系数、光发射功率和最优信号噪声失真比的影响。结果表明,射频本振调制器的最佳调制系数在载波数变化时可以保持不变,射频信号调制器的最佳调制系数和最优信号噪声失真比随载波数增大而减小,光发射功率随载波数增大而增大。     

极化聚合物薄膜电光系数的实时测量

提出了一种极化聚合物薄膜电光系数的实时测量方法。实验结构由耦合棱镜和依次制备在棱镜底面的四层薄膜组成,这四层薄膜分别是金属层（作为上电极）、极化聚合物,缓冲层和下电极。包含导波共振角并具有一定角度的入射光线会聚于棱镜底面,然后用CCD探测拍摄反射光斑,当外加电场作用于上下电极时,就可从光斑暗线位置的变化测量极化聚合物薄膜的电光系数。在测量过程中,使用了计算机图像处理方法和光学空间滤波技术。     

SiO2基光纤型电光调制器

提出一种新型LiNbO3光纤型电光调制器。用LiNbO3光纤制成的M-Z干涉计置于SiO2基体上,在铌酸锂光纤上部制作电极完成该调制器制作。利用有限元法对非对称共面带线（ACPS）和对称共面带线（SCPS）两种电极的光纤型调制器微波等效折射率、调制带宽和特性阻抗进行分析。在工作波长1．5μm下,SCPS电极光纤型调制器宽带74．03GHz,半波电压为2．29V;ACPS电极光纤型调制器宽带可达82．25GHz,半波电压为1．37V。结果表明,后者性能优于前者,但两种电极的光纤型调制器都可获得大带宽、低半波电压和良好的阻抗匹配。     

单晶集成的1×N电光开关

为了使光学系统更加紧凑化和稳定化,本文提出了一种单晶集成的1xN电光开关:它有2个折射面,4个互相垂直的全内反射面,和N-1个电光调制器.还得到了该种1×N电光开关的构成条件:发生两相邻反射的反射面必须互相垂直.并对晶体的结构进行了优化,通过调整光束输出面与光轴的夹角来改变光束出射角,使得接收端易于接收输出的光信号.给出1×3电光开关的实例.     

有机极化聚合物材料及电光调制器件

有机极化聚合物材料是一类新型的功能高分子材料，在光电子及集成光学方面具有诱人的应用前景，其电光调制器件已接近实用化，本文综述了有机极化聚合物材料，极化聚合物体系及电光调制器件的研究进展，并指出它们存在的问题和发展方向。     

高复现性波片测量方法和实验

建立了一种高精度波片位相延迟量的测量装置，它以磁光调制式１／４波片法为基础，其测量精度优于ＫＤＰ电光调制检测法。本文介绍了磁光调制器的设计，总结了磁光调制方法的最优解调特性，提出了测量装置的结构，其中强调了磁光调制器必须放置在标准１／４波片之后以满足最优解调特性。误差分析表明，环境温度和机械安装是影响测量精度的重要因素。实验对同一批波片进行了长时间多次重新安装测量，其复现精度优于２０′     

基于光器件调制的高增益射频放大电路研究

该设计实现了0～6 GHz频率范围内增益可调的高摆幅电光调制驱动电路,用于铌酸锂相位调制器和强度调制器的信号调制。该电路可将各种编码方式的高速串行随机数放大到10 V峰峰值电压。此外,该电路还支持程控调节输出摆幅功能,可根据需要实时调节输出信号的大小,非常适用于高速光纤通信系统、量子通信等领域。该电路具有高带宽、高摆幅、低噪声、高稳定性、高可靠性、使用方便、低成本等特点,有利于设备的量产化。     

Determination of the refractive index and the chiral parameter of a chiral solution based on chiral reflection equations and heterodyne interferometry

This study develops a method for determining the chiral parameter and the refractive index of an isotropic chiral medium using chiral reflection equations and critical angle phenomena. Linearly polarized light propagates back and forth in a parallelogram prism between two parallel compartments with chiral solutions. A beam splitter then divides the light that emerges from the prism into a reflected light beam and a transmitted light beam. The two beams pass through a compensator and an analyzer, respectively, to cause phase compensation and interference of s and p polarizations. The phase difference between the two interference signals are initially optimized by a suitable optical arrangement and subsequently measured by heterodyne interferometry. Additionally, the refractive index of the solution is determined from the critical angle that occurred at the discontinuity of the phase difference between the two interference signals. These results are substituted into derived equations to calculate the chiral parameter. The approach has the merits of both common-path interferometry and heterodyne interferometry.     

Advanced Optical Techniques

The development of a digital electro-optic light beam deflector (DLD) is described. Each deflection stage consists of a DKDP polarization switch with a coating of transparent electrodes (longitudinal electro-optic effect) and a calcite prism for angular deflection. Effects which limit the switching frequency and the capacity speed product (i.e. product of the number of resolvable beam directions and the switching frequency) are theoretically investigated. A four-stage solid-state DLD has been realized which operates at switching frequencies up to 10 kHz and at a random access time of 30 μ s. The system is going to be expanded to 8 × 8 stages for the addressing of 256 × 256 beam directions.     

Electro-optic polymer light modulator based on surface plasmon resonance

The first experimental results, to our knowledge, for an optical modulator that makes use of an electro-optic polymer located between two thin silver films are presented. The methods used to fabricate the modulator are discussed. Initial results show 18.5% modulation in the intensity of the light reflected off of the modulator at a wavelength of 6328 ?.     

Action from tunable periodic structures. II. Experimental observation of electric field-induced diffraction peaks

As previously predicted [Appl. Opt. 40, 5583 (2001)], we have now observed electric field-induced diffraction peaks in transmission and reflection experiments by use of a LiNbO3 sample with interdigital planar electrodes that serve as a diffraction grating. The magnitudes of the new peaks in the reflection experiments are ten times larger than those in the transmission experiments. We interpret these effects in terms of a field-induced refractive-index change produced by the linear electro-optic effect. The positive and negative changes in the refractive index produce two diffraction gratings that are period doubled with respect to the original grating and that have a phase difference between them. The superposition of the diffracted light from these gratings is shown to account for the new peaks. From the relative magnitude of the new peak to that of the central peak, we estimate the refractive-index change to be 0.004.     

High-Contrast Spatial Light Modulator by use of the Electroabsorption and the Electro-Optic Effects in a GaAs Single Crystal

A new spatial light modulator that uses the electroabsorption and the electro-optic effects in a GaAs single crystal is proposed. The device has the same structure as a Pockels readout optical modulator and can be operated at a frame rate higher than 500 Hz. When the electroabsorption and the electro-optic effects are combined, the dynamic range (contrast ratio) becomes larger than that which results when either effect is used singly. It was experimentally confirmed that the modulator has a high contrast ratio (greater than 2000:1), high sensitivity, and consequently large gamma characteristics.     

Device for magneto-optic signal detection with a small crystal prism

A device made of a birefringent crystal for signal detection of magneto-optic (MO) disks is presented. The light beam from a MO disk is separated into two orthogonally polarized components at the surface of a birefringent prism. After these two components are reflected by the top and the bottom surfaces of the prism inside, at the detector they become sufficiently separated from each other for discrete detection, even though the prism is small. A method for calculating the light intensities and the positions of focused beams in a birefringent prism and the results of a fundamental experiment are presented.     

Spectroscopic ellipsometer based on direct measurement of polarization ellipticity

A polarizer-sample-Wollaston prism analyzer ellipsometer is described in which the ellipsometric angles ψ and Δ are determined by direct measurement of the elliptically polarized light reflected from the sample. With the Wollaston prism initially set to transmit p- and s-polarized light, the azimuthal angle P of the polarizer is adjusted until the two beams have equal intensity. This condition yields ψ=±P and ensures that the reflected elliptically polarized light has an azimuthal angle of ±45° and maximum ellipticity. Rotating the Wollaston prism through 45° and adjusting the analyzer azimuth until the two beams again have equal intensity yields the ellipticity that allows Δ to be determined via a simple linear relationship. The errors produced by nonideal components are analyzed. We show that the polarizer dominates these errors but that for most practical purposes, the error in ψ is negligible and the error in Δ may be corrected exactly. A native oxide layer on a silicon substrate was measured at a single wavelength and multiple angles of incidence and spectroscopically at a single angle of incidence. The best fit film thicknesses obtained were in excellent agreement with those determined using a traditional null ellipsometer.     

Infrared broadband 50%-50% beam splitters for s-polarized light

Prisms and slabs made of high-refractive-index materials such as ZnSe, Ge, and Si can be designed as broadband, 50%-50%, beam splitters (BSs) for obliquely incident s- polarized light in the near- and mid-IR. The beam-splitting face of the prism or slab is uncoated, while the exit face is antireflection coated. The split beams travel in orthogonal directions when light is incident at the Brewster angle. A novel design is also described that uses Brewster-angle reflection at the SiO2-Si interface to achieve a 50%-50%s-polarization BS over the 1.2-3.5 microm spectral range. Such s-polarization BSs are particularly suited for interferometry and holography.     

Generation of Phase-Modulated Periodic Optical Signals by use of a Polarization Interferometer

Polarization phase-shifting interferometry is an established technique in optical metrology. In the present study it is shown that, by use of this technique, not only is it possible to realize any discrete magnitude of a predetermined phase difference (from 0 to 2pi) between two light beams but also phase-modulated periodic optical signals can be generated simply by rotation of a polarizer or a retarder or both placed at the input of a conventional two-beam interferometer. Some representative linear and nonlinear periodic polarization-induced phase-modulated optical signals are shown. A linear phase modulation of 0-2pi with constant output intensity is obtained in some cases. The Poincaré sphere representation is introduced as a convenient tool for visualizing the dynamics involved in the generation of polarization-phase-modulated waveforms and as a possible aid to intelligent modification of the generated waveform as required. This all-optical technique of continuous and periodic phase variation should prove useful for introducing phase modulation without the need for electro-optic devices.