Investigations of the E-O behavior in the poled polymer waveguide

The electro-optic (E-O) properties of the slab polymer waveguide induced by electric poling have been studied experimentally. The thin film waveguide was prepared by a synthesized polymer polypelargonamide and poled by applying voltage between the electrodes. I–V curves and E-O characteristics of the polymer films were in-situ measured during poling. In order to evaluate the molecular dipole orientation under the poling field, the absorption spectra of this film was observed by FTIR. The E-O performance of the polymer slab film was also estimated by the Mach–Zehnder interferometer.     

Submicron External Electro-optic Measuring System Based on an Electro-optic Solid Immersion Lens

In this paper, all electro-optic solid immersion lens (EOSIL) is introduced, which is made of GaAs. A reflecting external electro-optic measuring system based on the EOSIL is built. With a hemispherical GaAs EOSIL used as the external probe, 0.7 µm spot size is obtained when the wavelength of the probing beam from a laser diode is 1.3 µm and a microscope objective with 0.3 numerical aperture is used. The principle of the measuring system is analyzed by Jones matrix. By using the system, the electrical signals propagating on a microstrip transmission line are successfully measured. The voltage sensitivity about 5 mV/ is measured when 10 kHz sinusoidal electric signal is applied on the microstrip line.     

Integrated optical cross strip polarizer concept

Passing across an abrupt junction from a thick vertically bimodal waveguide to a thinner single mode segment, guided light can undergo complete destructive interference, provided that the geometry and the phases of the modes in the initial segment are properly adjusted. We propose to employ this effect to realize a simple polarizer configuration, using a strip that is etched from a planar waveguide. A beam of light is made to pass the strip perpendicularly. The light enters from the single mode waveguide outside the strip into the strip segment, which is configured to support two modes. At the end of the strip, apart from reflections, the amount of power that is guided in the following lower segment depends on the local phases of the two modes. These phases are different for TE and TM light, hence we may expect a polarization dependent power transfer, resulting in polarizer performance for a properly selected geometry. The paper describes in detail the modeling of the device in terms of rigorous mode expansion. Design guidelines and tolerance requirements for geometric and material parameters are discussed. For typical Si₃N₄/SiO₂ materials, our calculations predict a peak performance of 34 dB polarization discrimination and 0.3 dB insertion loss for a device with a total length of about 12 m that selects TE polarization at a wavelength of 1.3 m.     

一种边缘提取的图像分割方法

图像分析技术从广义上来讲 ,是指从图像中提取有用的数据或其它信息。图像分割是图像分析技术的重要手段 ,在前人的理论基础上经过实验提出了一种边缘提取的图像分割方法———行扫描空间带通滤波法。该方法在电视图像的自动跟踪识别中取得了很好的效果 ,是一种较为可取的图像分割方法     

向列相液晶中强非局域空间光孤子传输的理论研究

对向列相液晶中非局域空间孤子的传输进行了理论研究.基于非线性液晶孤子传输方程，采用Gauss形式的试探解，不仅得到了空间孤子的解析解,而且还在临界功率附近得到了呼吸子的解析解.通过数值模拟证明我们的结果比Conti和Assanto等人的结果更合理.同时，对液晶中的非局域孤子模型和Snyder等提出的强非局域孤子模型进行了全面的比较. 关键词： 向列相液晶 空间孤子 非局域非线性 呼吸子     

利用迈克耳孙干涉仪重建蜡烛火焰温度场

利用教学实验中的迈克耳孙干涉仪,进行蜡烛火焰温度场的测量.对干涉条纹进行了处理和细化,并分别用阿贝尔变换法和环带法对蜡烛火焰的温度场进行了计算,得到蜡烛火焰横截面上温度场的定量结果.     

A Method for Measuring the Three-Dimensional Refractive-Index Distribution of Single Cells Using Proximal Two-Beam Optical Tweezers and a Phase-Shifting Mach—Zehnder Interferometer

This paper describes a method for measuring the three-dimensional (3D) refractive-index distribution in a single cell. The method can be used to observe the distribution of cell components without fluorescence staining. The two-dimensional optical path length distributions from multiple directions are obtained by non-contact rotation of the cell. These optical path lengths are converted into the line integrals of the refractive index, and the 3D refractive-index distribution is reconstructed by means of computed tomography. The refractive-index distribution in a breast cancer cell can be measured using a phase-shifting Mach—Zehnder interferometer in conjunction with proximal two-beam optical tweezers.     

Angular interferometer using calcite prism and rotating analyzer

An interferometer using a calcite prism and rotating analyzer is proposed for angular displacement determinations. The calcite prism senses the angular displacements and the rotating analyzer transfers the interference signals from dc-type into ac-type. Compact optical setup and using low-cost devices are thus the advantages of the interferometer. The theory of the interferometer is first demonstrated. A setup constructed to realize the interferometer and the results of using this setup are then presented.     

Holographic vibration measurements of rough surfaces using a LCSLM

This paper describes measurements of a vibrating object with rough surface by the time-averaged method of holography using a newly designed optically addressed liquid crystal spatial light modulator with a resolution of 102 lp/mm and a diffraction efficiency of 16%. An object vibrating faster than several tens of Hz could be visualized. The pattern obtained by the method provides the locus of vibrating nodes. The advantage of this method is that a high contrast pattern of a vibrating object can be imaged in near-real-time, although the sensitivity of vibration is decreased.     

Optimization of peak power of passively Q-switched lasers by taking into account intracavity laser spatial distribution

The intracavity photon density and the initial population-inversion density in the diode-pumped passively Q-switched lasers are assumed to be Gaussian spatial distributions. The space-dependent rate equations are solved numerically. The key parameters of an optimally coupled passively Q-switched laser under Gaussian approximation are determined, and a group of general curves are generated for the first time. These key parameters include the optimal normalized coupling parameter and the optimal normalized saturable absorber parameter that maximize the peak power, and the corresponding normalized energy, normalized peak power, and normalized pulse width. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the saturable absorber, and the resonator. In addition, the importance including the space variation is also shown. The optimal calculations for a diode-pumped passively Nd:YVO₄ laser are presented to demonstrate the use of the curves and the related formulas.