Nonlinear Optical Rotatory Dispersion: Application of Group Theoretical Statistical Mechanics

Abstract

The third principle of group theoretical statistical mechanics is used to define the existence of many new nonlinear optical rotatory phenomena caused by the interaction of intense electromagnetic radiation with molecular ensembles. This treatment removes the necessity of having to distinguish between ‘natural’ and ‘magnetic’ optical activity; both processes emerge consistently from the analysis, which is based on an application of the Hellman-Feynman theorem and a double Taylor expansion of the induced electric and magnetic dipole moments.     

Coefficients of a Dispersion Equation for the Birefringence of a CdGeAs(2) Nonlinear Crystal at Different Temperatures

Birefringence (B(f)) and its temperature derivative (dB(f)/dT) determine the temperature characteristics of nonlinear optical laser devices. The birefringence and its dispersion for a CdGeAs(2) nonlinear crystal are analyzed critically by use of a recently introduced, physically meaningful, dispersion equation at different operating temperatures from 14 to 450 K, which fits reasonably well with the experimental data. This equation is based on the average electronic absorption gap and the lattice absorption gap at the short- and long-wavelength transparency limits, respectively.     

Optical Waveguide Lenses

The development of optical waveguide lenses, i.e. mode-index (including Luneburg), geodesic, Fresnel and Bragg grating lenses is briefly reviewed chronologically. A Bragg lens and a Luneburg lens, fabricated by electron lithography and vacuum deposition respectively, are described. A nearly diffraction-limited lens of the latter type can be obtained by using the shadow mask process.     

Nonlinear Coefficients and the Effective Area of Cross-phase Modulation Coupling of LP01 Optical Fibre Modes

Abstract

The dispersion relations of two nonlinearly interacting LP₀₁ modes are derived from a perturbation procedure. A step-index optical waveguide is considered here, but it should be emphasized that other index profiles can be introduced without any increase in conceptual difficulty. The cross-phase modulation couples waves with the same polarization and different frequencies. The nonlinear contributions to the linear wavenumbers arising from the effects of both self-phase and cross-phase modulation are obtained. The method used for deriving the nonlinear dispersion coefficients is novel because it uses nonlinear changes in the wave-field distribution in the transverse direction. As a consequence, the results differ from those obtained by the usual method of determining the nonlinear wavenumber shift. A set of coupled nonlinear Schrödinger equations is considered and a new nonlinear effective area involved in the cross-phase modulation effect is defined.     

圆柱壳中结构振动波的传播特性

计算了圆柱壳中低阶和高阶周向模态结构振动波的频散结果，得到了相应的频散曲线。着重分析了近场波和衰减驻波的性质及其随频率变化的规律，结果表明：纵向伸缩近场波和扭转近场波都不具有通常意义上的纵向伸缩和扭转的性质，弯曲近场波则具有通常意义上弯曲性质；衰减驻波大体上是弯曲性质的驻波。文中把低阶和高阶周向模态情况下波的频散规律也作了比较。     

A Linearized Approach for Diffraction-free Propagation in a Planar Nonlinear Waveguide

Abstract

The aim of this paper is to show that the superposition of three waves (one strong and two weak), under suitable conditions, can create diffraction free propagation in a nonlinear planar waveguide. The propagation is described by the nonlinear Schrödinger equation, which is suitably linearized.     

GaAs Mach－Zehnder型光波导开关／调制器

采用非对称Ｘ结耦合器代替传统的Ｙ分支器，研制了ＧａＡｓＭａｃｈ－Ｚｅｈｎｄｅｒ型２×２光开光，得到了小于－２２．４ｄＢ的串音比和１２Ｖ左右的开关电压，器件的波导传输损耗小于７ｄＢ／ｃｍ。预计该器件可广泛应用于ＧａＡｓ开关列阵及高速光调制等领域。     

基于环氧树脂硅烷的平面光波导的制备与表征

采用无水溶胶-凝胶合成方法,以二苯基二羟基硅烷(Diphenylsilanediol,DPSD)和γ-缩水甘油醚氧丙基三甲氧基硅烷(γ-glycidoxypropyl-trimethoxysilane,GPTS)为先驱体,制备出有机-无机杂化光波导材料,并在石英玻璃基片上旋涂制得平面光波导薄膜.用Abbe折射仪测试薄膜...     

Asymptotic Coupling Coefficients of Well-separated Single-mode Optical Waveguides

Abstract

Simple general formulae for the coupling coefficients of the fundamental modes on well-separated parallel optical waveguides are derived. The calculation merely requires accurate knowledge of the propagation constants and core fields of the modes on the individual waveguides, while the far-from-core fields need not be known. Results for coupled circular fibres are identical with the asymptotic expansions of previously derived exact coupling coefficients. Analytical expressions for the coupling coefficients between the fundamental modes on identical weakly guiding channel waveguides are obtained.     

Nonlinear Optical Properties of a Soluble Form of Polyisothionaphthene

Abstract

The third-order nonlinearity of a low-bandgap conjugated organic polymer has been assessed. Degenerate four-wave mixing experiments (at 1·064 μm using picosecond pulses from a passively mode-locked neodymium-doped yttrium aluminium garnet laser) on solutions of the polymer have permitted the determination of the microscopic third-order nonlinearity γ. The polymer exhibits unusual behaviour which is solution concentration dependent. This behaviour is thought to be due to aggregation effects and strongly suggests that the bulk response of the material is large, the third-order nonlinearity being of the order of ten times greater than that of polythiophene.     

Erbium Doped Phosphate Glass For Optical Waveguide Amplifier

Erbium (Er3+) doped phosphate glasses was prepared and the optical properties of these glasses were investigated. The emission parameters were calculated using the Judd-Ofelt treatment. The radiative lifetime of the 4I13/2 level is calculated to be 7.2ms. The fluorescence lifetime is measured to be 6ms, and the quantum efficiency is estimated to be 83%. Ion-exchanged optical waveguides were fabricated in these glasses by using pure KNO3 meet at 370℃, and diluted AgNO3 molten salt at 270℃. It was found that the lower temperature diluted AgNO3 molten salt is better for the ion exchange process. Planar waveguide with 5 modes at the 633nm and 2 modes at the 1550nm was demonstrated using the diluted AgNO3. Our results show that phosphate glass is a potential candidate for the 1.5μm optical amplifier device.     

Analysis of Waveguide Ring Lasers with Nonlinear Directional Outcoupler

Abstract

The waveguide ring laser with the light outcoupled through the nonlinear directional coupler is analysed theoretically. The influence of the characteristic system parameters on the laser radiation for two configurations of the laser is presented. In particular, the stability of the laser radiation is studied in details.     

集成光波导器件的计算机辅助设计软件的开发

报导了最新开发的集成光波导器件的计算机辅助设计软件─—IOCAD2，它是一个采用复折射率矢量束传播分析方法的三维模拟分析软件。本文介绍了它的功能、特点、使用方法以及适用条件，并且以SLD直条形波导吸收区为例进行了模拟，得到了很好的模拟结果。     

Erbium Doped Phosphate Glass For Optical Waveguide Amplifier

Erbium (Er3+) doped phosphate glasses was prepared and the optical properties of these glasses were investigated. The emission parameters were calculated using the Judd-Ofelt treatment. The radiative lifetime of the 4I13/2 level is calculated to be 7.2ms. The fluorescence lifetime is measured to be 6ms, and the quantum efficiency is estimated to be 83%. Ion-exchanged optical waveguides were fabricated in these glasses by using pure KNO3 meet at 370℃, and diluted AgNO3 molten salt at 270℃. It was found that the lower temperature diluted AgNO3 molten salt is better for the ion exchange process. Planar waveguide with 5 modes at the 633nm and 2 modes at the 1550nm was demonstrated using the diluted AgNO3. Our results show that phosphate glass is a potential candidate for the 1.5μm optical amplifier device.     

集成光学非球面消球差双凸波导透镜的研制

针对微透镜制作采用的球透镜研磨,多组分玻璃基板离子交换,结晶化玻璃基板光热法,本文提出非球匠消球差双凸波导透镜设计、制备及参数测试方法.该方法根据集成光学原理,研制了一种非球面消球差双凸波哥透镜.该透镜数值孔径大,放大倍数高,接近衍射极限,采用光刻、复制工艺,结构简单,一致性好.实验结幂表明,NA=0.35,β=6.932,光强分布与理论值一致,达到设计要求.     

Optical Generation of Gabor's Expansion Coefficients for Rastered Signals

Gabor's expansion of a signal into a discrete set of properly shifted and modulated versions of an elementary signal is introduced; several examples of elementary signals are considered. An arrangement is described which is able to generate Gabor's expansion coefficients of a one-dimensional signal by optical means. An important feature of the optical arrangement is that it accepts the one-dimensional signal on a raster format; hence, the two-dimensional nature of the optical processing system is fully utilized.