Numerical analysis of In0.53Ga0.47As/InP single photon avalanche diodes

A rigorous theoretical model for In 0.53 Ga 0.47 As/InP single photon avalanche diode is utilized to investigate the dependences of single photon quantum efficiency and dark count probability on structure and operation condition.In the model,low field impact ionizations in charge and absorption layers are allowed,while avalanche breakdown can occur only in the multiplication layer.The origin of dark counts is discussed and the results indicate that the dominant mechanism that gives rise to dark counts depends on both device structure and operating condition.When the multiplication layer is thicker than a critical thickness or the temperature is higher than a critical value,generation-recombination in the absorption layer is the dominative mechanism;otherwise band-to-band tunneling in the multiplication layer dominates the dark counts.The thicknesses of charge and multiplication layers greatly affect the dark count and the peak single photon quantum efficiency and increasing the multiplication layer width may reduce the dark count probability and increase the peak single photon quantum efficiency.However,when the multiplication layer width exceeds 1 μm,the peak single photon quantum efficiency increases slowly and it is finally saturated at the quantum efficiency of the single photon avalanche diodes.     

手性分子介质非线性光学研究新进展

文章介绍了近年来手性分子介质及材料的非线性光学性质的研究状况，综述了手性分子非线性微观模型的使用情况，给出了一些典型的二阶、三阶非线性光学实验结果，用这些微观模型可以正确地分析这些结果．同时指出了未来研究的趋势，及研究成果可能应用的领域．     

A Novel All-Optical Switch in a Double-Loop Sagnac Ring Coupled with a Nonlinear Ring Resonator

We propose a novel configuration of all-optical switch based on a double-loop Sagnac ring coupled with a nonlinear ring resonator. In the case of self-phase modulation, the reducing switching threshold power clown to mW is predicted, which is the improvement of earlier works on all-optical switches. The switch optimization is analysed.A way to increase the response speed of all-optical switches is suggested.     

应用平衡双光纤光栅动态解调技术测量应力的研究

报道了一种基于解调技术使用双光纤光栅测量张力的方法。在外界拉力下一个光纤布拉格光栅反射波长的漂移被转变成从另一个被压电陶瓷片调制的光栅反射的光脉冲间隔的变化。实验表明，当测量一个40N以内的力时，测量精度可达到2．5mN。     

掺铒光纤非线性耦合器的实验研究

提出一种耦合参量可用光调控的掺铒光纤非线性耦合器.用熔融拉锥法熔合两根掺铒光纤，拉制成工作波长为155nm的3dB掺铒光纤耦合器.通过调变输入耦合器一臂的980nm泵浦光功率，可以改变两臂的传播常量差，从而改变耦合器两臂信号光的相对输出功率.通过测量输入泵浦光功率和两臂信号光输出功率，得到直通臂耦合比依赖于泵浦光功率的实验曲线.实验研究表明，当泵浦光功率从0 mW变化至20 mW时，耦合比的变化可达到40％.与理论模拟的结果一致.     

有机分子系统中反饱和吸收向饱和吸收转化的条件

由多能级稳态速率方程导出反饱和喟收向饱少吸收转化的能级参数条件和阈值光强，并与动态理论导出的结果作了比较，讨论了阈值光强在光限幅材料设计中的应用。     

C60溶液中的暗空间光孤子及其诱导的柔性光波导

利用Ａｒ＾＝激光在Ｃ６０甲苯溶液中产生的自散焦效应观察到暗空间光取子以及由它诱导出的柔性光波导现象。通过对非线性薛定谔方程的数值计算，模拟了暗空间孤子的形成过程，获得与实验相符的结果。     

EXCITED-STATE NONLINEAR ABSORPTION AND ITS APPLICATION IN PHOTONIC TECHNOLOGY

The main achievements in our research on the physical phenomena of the excited-state nonlinear absorption in a molecular system and its applications in photonic technology are described. In the first part of this paper, some energy-level models and rate-equations are used to explain various mechanisms of the excited-state nonlinear absorption under differ-ent conditions, such as reverse saturable absorption caused by the triplet and/or the singlet excited-state absorption; saturable absorption due to the first and/or the second singlet excited-state absorption; and the excited-state nonlinear absorption induced by two-photon absorption. The experimental results for metal-organic and C₆₀ materials irradiated by ps and ns laser pulses are consistent with the simulated curves of the transmittance versus flu-ences. In the second part, the applications of excited-state nonlinear absorption in photonic techniques including optical bistability, optical switching, optical limiting, optical modula-tion, optical logic and optical storage are introduced. The working principles of the photonic devices based on the excited-state nonlinear absorption are presented. The experimental characteristic curves are found in good agreement with the theoretical simulations for these devices.     

光学双稳态装置研究进展

光学双稳性(Optical Bistability)是光波通过某种光学装置强度发生非线性变化的特性,　对应某一输入光强存在着两个或多个稳定的输出光强状态.这是属于量子电子学的非线性光学领域的一个新研究课题.利用光学双稳性可以制成具有光开关、光存储、光放大等功能的光学器件,具有开关     

具有非线性反馈的光学双稳态装置

一、前 言 双稳态光学器件(BOD)具有双稳态电子器件类似的功能,可以用作存储器、放大器、振荡器、限幅器和开关元件等.如果实现微型化,做成集成光路元件,其开关速度估计可达1ns对于光学信息处理和光通讯的应用具有重要意义,可能成为未来光学数字计算机的一种基础逻辑元件.因而近年来引起人们的重视. 目前国外研究的BOD器件有两种类型,一类是纯光学的。即将非线性光学介质(如饱和吸收染料,金属蒸汽等)置于F-P谐振腔中构成;另一类是光电结合的,即利用电光普克尔效应构成.而电光BOD器件主要有两种方案:一种是P,W,Smith等人提出的F-P谐振…