一种基于双波长的光声测温技术

光声测温是一种利用光声效应来进行温度监控的新方法,具有非侵入式、高灵敏度和探测深度较深等优点.但现有的单波长光声测温方法极易受到系统及测量环境干扰而导致测量精度降低.为了解决这一问题,本文提出了一种双波长光声温度测量方法.在光声测温理论的基础上,分析推导了双波长光声测温的基本原理,并进行了仿体及离体组织样品的双波长光声测温实验.实验结果显示,与传统单波长模式相比,双波长模式下的光声温度测量误差明显减小,测量精度平均提高35%以上.研究结果表明双波长光声测温方法能够有效提高光声温度测量的精度和稳定性,可作为一种更精准的光声温度监控方法应用于医疗手术等领域.     

基于光子晶体光纤中双抽运四波混频效应的非归零到归零码型转换实验研究

提出并实验证实了利用色散平坦高非线性光子晶体光纤中双抽运四波混频效应实现非归零 (NRZ)到归零(RZ)码型转换的新方案, 将一束NRZ信号光与两束同步时钟脉冲光同时注入光子晶体光纤, 通过双抽运四波混频效应产生两个闲频光, 经过光学滤波后即可完成单到双全光NRZ-RZ码型转换. 与基于常规单抽运四波混频效应的码型转换方式相比, 本设计方案由于采用了双抽运四波混频效应, 因此具有双路组播信号波长可彼此独立选取的优点. 分析了码型转换器的波长调谐性及对输入光功率波动的容忍性, 得到转换信号的最优消光比和Q 因子分别为15 dB和5.4. 研究结果表明, 本方案既具有对比特率和调制格式透明的优点, 又避免了使用单抽运四波混频效应进行码型转换时两路组播信号波长相互制约的弊端, 且实现了全光波长转换和波长组播功能. 关键词： 码型转换 四波混频 双抽运 光子晶体光纤     

Y型四能级中的双电磁感应透明和超窄吸收

采用密度矩阵方程．对双光场耦合的分子Y型四能级系统的粒子数分布和吸收特性进行了计算和分析,在此能级系统中得到了双暗态共振和双电磁感应透明．并讨论了相应的物理机制。同时,我们讨论了Y型四能级两个上能级的自发辐射产生的量子干涉效应对电磁感应透明的影响,发现自发辐射干涉相消可以产生超窄线宽和导致探测光的吸收增强,自发辐射干涉相长可以展宽谱线和减弱探测光的吸收,并运用缀饰态理论对以上计算结果进行分析,与采用密度矩阵方程的计算结果一致。     

边角效应对辉离子渗金属加工的影响

在采用双辉光放实施的离子渗金属加工中，存在强烈的边角效应。从等离子体性能入手，在实验研究了这种边角效应，并分析了该种边角效应产生的原因，讨论了它对双辉光放电离子渗金属和加工的影响。     

边角效应对双辉离子渗金属加工的影响

在采用双辉光放电实施的离子渗金属加工中，存在强烈的边角效应。从等离子体性能入手，实验研究了这种边角效应，并分析了该种边角效应产生的原因，讨论了它对双辉光放电离子渗金属加工的影响。     

ZnS光学双稳性器件中的不稳定性

本文首次报道ZnS干涉滤光片双稳器件中的自再生脉冲现象,并对器件产生这一不稳定性的条件和过程进行了分析及模拟计算,该器件有可能作为光学脉冲发生装置用于数字光计算研究,演示了光计算回路的逻辑功能.     

半导体光放大器中垂直双抽运四波混频效应的理论研究

建立了输入信号光偏振方向任意情况下的半导体光放大器(SOA)中 垂直双抽运四波混频(FWM)效应的完整宽带理论模型. 以基于SOA的垂直双抽运FWM型全光波长转换器为例, 通过数值模拟的方法, 理论研究了输入信号光与两抽运光功率、两抽运光与信号光之间的波长失 谐量和输入信号光偏振方向等工作参数对SOA的垂直双抽 运FWM效应及基于SOA的垂直双抽运FWM型波长转换器特性的影响.     

Ar原子序列双光双电离产生光电子角分布的理论计算

基于多组态Dirc-Fock方法和密度矩阵理论,给出了原子序列双光双电离光电子角分布的计算表达式,发展了相应的计算程序.利用该程序对Ar原子3p壳层序列双光双电离过程进行了理论研究,给出了光电离的总截面、磁截面、剩余离子取向以及光电子角分布的各向异性参数与入射光子能量的函数关系.结果显示在光电离截面的Cooper极小位置附近取向参数出现极大值,而光电子角分布的各向异性参数在该位置附近出现极小值.进一步给出了33.94和55.34 eV光子能量下序列双光双电离过程中第一步的Ar原子和第二步的Ar^+离子3p壳层光电子角分布,分析了序列双光双电离光电子角分布与单光电离光电子角分布的差异.将计算结果与文献已有的数据进行了比较,具有很好的一致性.本文的研究结果对揭示光与物质相互作用的非线性动力学机制具有重要的参考价值.     

双条形电极结构AlGaInP-LED微阵列器件的设计和实验研究

设计了一种基于AlGaInP发光材料的像素为320×240、单元像素面积为100 μm×100 μm 微型LED阵列。通过仿真和分析,设计了一种双条形电极结构。考虑到不同电极宽度下的电流分布情况以及电极的遮光效应,设计了电极宽度为13 μm 的优化电极结构,使得每个发光像素的表面出光面积比为50.15%,并分析了电极对有源层出射的光的反射影响。制定了基于MOEMS工艺的微型LED器件的制作流程并进行了基本实验研究,最终给出了制作出的上电极的单个单元照片。     

SOI无间距定向耦合光开关模型分析及设计

提出了一种简便可行的ＳＯＩ无间距定向耦合光开关（ＢＯＡ型－Ｂｉｆｕｒｃａｔｉｏｎ Ｏｐｔｉｑｕｅ Ａｃｔｉｖｅ）模型分析方法，采用等离子体色散效应这种光开关的电学调制机理；而用ｐｎ结大注入效应分析开拳电学性质；并根据大截面单模ＳＯＩ脊形波导理论和上棕分析，设计了利用双模干淑机制工作的这种器件的结构参数和电学参数。     

End-pumped optical bistability Tm,Ho:YLF laser

We experimentally demonstrate strong optical bistability in a 2 μm continuous wave Tm,Ho:YLF laser with a bulk crystal. The laser is end-pumped by a 792 nm fiber-coupled laser diode. The bistable region is as wide as 1.6 W and the jump power at the turning point is as high as 82.5 mW when the temperature of the laser crystal is kept at 253 K. The influences of the cavity length and the transmission of the output coupler on the characteristics of optical bistability are obtained. The theoretical analysis shows that the bistable output in the Tm,Ho:YLF lasers comes from the combined effects of the nonlinear saturation of ground state reabsorption, the energy transfer upconversion, and the excited state absorption.     

端面抽运Tm，Ho：YLF激光器双稳特性的理论分析与实验研究

报道了波长为792nm激光二极管端面抽运Tm,Ho：YLF连续激光器的双稳输出特性.在考虑能量传递上转换和基态对2μm激光重吸收的前提下,建立了Tm,Ho：YLF双稳激光器准三能级速率方程理论模型.通过对Tm,Ho：YLF激光器速率方程的求解,理论预见了Tm,Ho：YLF激光器双稳输出的特性,并分析了其产生的机理.进行了激光二极管端面抽运Tm,Ho：YLF激光器双稳输出的实验研究,当激光晶体温度为253K时,双稳区的宽度可达1.6W,跃变点输出功率的跃变量可达82.5mW.通过对比发现理论结果与实验结果比 关键词： 端面抽运 Tm Ho：YLF晶体 连续输出 光学双稳     

Optical feedback effect on bistable laser diodes

The optical feedback effect on multi-section bistable laser diode characteristics, especially on light/current hysteresis, has been studied. A decrease in the bistable laser diode hysteresis width under optical feedback was observed for the first time. A theoretical analysis has been carried out by solving carrier density rate equations, combined with the light-field equation. The analysis shows that the observed hysteresis width decrease is due to the phase detuning, which is governed by the difference between the values of the α-parameters (line-width enhancement factors) in the gain section and the loss section.     

Optical bistability effects in a Tm,Ho:YLF laser at room temperature

We demonstrate strong optical bistability in a 2 microm continuous-wave Tm,Ho:YLF laser pumped by a 792 nm laser diode near room temperature. The bistable region is as much as 100 mW wide at 283 K and can be controlled by the temperature of the laser crystal. The influence of crystal temperature on the characteristics of optical bistability is obtained. The influence of the pump-to-mode ratio on the bistable characteristics of the laser is also discussed. To our knowledge this is the first report of optical bistability effects in Tm,Ho:YLF lasers.     

Manipulating a micro-cantilever between its optomechanical bistable states in a lever-based Fabry-Pérot cavity

In this paper, we demonstrate experimentally switching a cantilever between its optomechanical bistable states in a low finesse optical cavity. Our experiment shows that the deformation of cantilever can be manipulated by tuning the cavity resonance. When the laser power increases across the threshold value of 110 ?W, optomechanical bistability is induced by strong static photothermal backaction at room temperature. Numerical calculation revealed that the bistable effect originates from the multi-well potential created via the optomechanical interaction. Switching of the cantilever between the bistable states was achieved by tuning the cavity to the corresponding boundaries of the bistable region, where the barrier between the bistable states vanishes.     

Semiclassical theory of optically bistable laser by output-feedback pumping scheme

Steady-state solutions of the output-feedback pumped bistable laser(OFPBL)have been obtained using the semiclassical laser equations.A linear-stability of the solutionshas been analysed.The results tell us that width of the hysteresis loop and the laser output in-tensity vary widely with the pump intensity and the intensity of input optical signal and thefeedback coefficient of the laser output as well as the other parameters.It shows that this typeof bistable laser is a kind of active optical bistable device which can be adjusted and controlledconveniently.     

Dynamics of an Optically Switched Bistable Semiconductor Laser

The switching time of an optically switched laser diode between a locked mode and free oscillation mode is studied. By starting with linear stability analysis, analytical expressions are developed to predict the switching time. It is shown that the switching of optical output between the locked and unlocked modes is governed by two relaxation processes with different time constants, and the change in the first relaxation process, dependent on the carrier density in the initial state, gives a strong effect on the total switching time, in contrast to the dynamic behavior of the carrier density dominated by a single relaxation process. Our analytical results show that larger detuning and power of optical input are effective in shortening the switching time and are believed useful to estimate the switching time of an optically switched bistable laser diode.     

有源-吸收分段式脊型波导半导体激光器的光双稳激射特性

本文报道了一种脊型波导有源-吸收分段结构半导体激光器中的光双稳输出特性的实验研究结果及其理论分析.给出了实验中发现的获取最大光滞回线宽度(Hysterisis)、所对应的器件结构参数以及电注入水平.此外,一种光线近似理论模型被采用来求解光输出特性从而得到了与实验近似一致的结果.     

光栅光学双稳态

本文报道了一种光栅光学双稳态装置.利用改变一对对称光栅间相对位移,实现了对透过光强的周期性调制.将这样的系统作为传输部分,分别用He-Ne激光和普通白光完成了光学双稳实验.实验结果与理论分析相符.