Optical Stabilizer Based on Optical Bistable Devices with All-Fibre Construction

We propose a fibre optical stabilizer constituted by a photoelectric-hybrid optical bistable device in which fibre Bragg grating is used as a light intensity modulator. The intensity noise-reducing ability is well improved through the method by employing two feed signals. As a result, the light intensity variation can be reduced to - 1/64.     

基于马赫曾德尔干涉原理的优化双锥结构应变温度同步传感

设计了一种基于光纤马赫曾德尔干涉仪的优化双凹锥结构。该结构通过单模光纤和保偏光纤之间使用不充分的电弧放电熔接制作而成,可以实现应变和温度的同步测量.凹锥中部的球形纤芯可以进一步地调控包层和纤芯中的光能量分布,经优化几何参数后的结构可以获得16 dB的干涉条纹消光比,大于相同参数下的双凹锥结构。传感实验表明所提出的结构在0～244.35με和25～50℃的范围内分别具有±1.616με和±0.79°C的高分辨率。由于交叉敏感导致两个参数的测量误差均小于1×10~(-3)%.这种结构为同时测量应变和温度提供了一种有效的方法,可应用于精密仪器测量中.     

多普勒振镜正弦调制多光束激光外差二次谐波测量微冲量

提出了一种正弦调制多光束激光外差二次谐波测量微冲量的新方法,将激光与工质靶作用产生的微冲量转化为扭摆的转动角度测量,基于激光外差技术和多普勒效应,把待测转角信息加载到外差信号的频率差中,经信号解调后可以得到待测转角值,通过多次测量取平均值的方法可以提高待测转角的测量精度,从而提高微冲量的测量精度。利用这种新方法,以PVC+2%C为工质靶,利用MATLAB仿真测量了激光与工质靶作用产生的微冲量,结果表明:该测量的最大相对误差小于0.8%。     

基于流量门限的提前预留竞争解决机制(英文)

基于小尺寸缓存的提前预留机制是有效的竞争解决方案.为支持区分服务,本文研究了两优先级提前预留机制的阻塞模型,分析了变化缓存尺寸与载荷比率条件下光突发交换网络核心节点的阻塞性能.为降低两优先级提前预留机制的突发丢弃率,提出一种基于流量门限的提前预留机制.数值分析确定了合理的缓存尺寸与流量门限,实现了高、低优先级间的缓存使用平衡.仿真结果表明:与原有提前预留机制相比,基于流量门限的提前预留机制保持了全流量状态范围内的阻塞性能,并明显降低了中、低流量状态内的突发丢弃率.     

基于延迟抢占的突发竞争解决策略

在光突发交换网络中, 将竞争突发送入光纤延迟线(FDLs)缓存以避免丢弃被认为是一种便捷、有效的竞争解决方案。基于“提前预留”模型, 提出采用延迟抢占(DP)的方式来实现突发的竞争解决, 比较了全延迟抢占与部分延迟抢占机制的阻塞性能。为支持区分服务, 开展了两优先级系统中延迟抢占机制的研究, 建立了适用于两优先级系统的阻塞分析模型, 并对不同配比条件下延迟抢占机制的阻塞及延迟性能进行了仿真分析。仿真结果表明, 延迟抢占机制有效地保证了高优先级突发的低阻塞要求, 与低优先级突发相比, 其突发阻塞率要低约2个数量级。此外, 由于FDL的长度固定, 数据突发的时延要求也得到了有效保障, 流量载荷ρ=1.0时, 高优先级突发的平均延迟仅为10 μs。     

半导体激光器混合功率控制系统

依据半导体激光器输出功率的噪音特性，提出一种采用模糊控制与比例控制结合的模数混合控制方案，稳定半导体激光器的输出功率．实验结果表明，混合光功率控制器能够对频率在10^6Hz数量级内的高、低频噪音均能够有效地抑制．静态测量下，光源输出功率的短期稳定度达到±0．55‰，长期稳定度达到±0．7‰。     

基于等效电路的半导体激光器热噪音特性仿真研究

通过引入Langevin噪音项的噪音等效电路研究了半导体激光器的热噪音特性．研究表明，在激光器的工作过程中，由于自加热效应所引来的热噪音是不能够被忽略的．本文基于半导体激光器的噪音等效电路，仿真分析不同频带宽度、不同注入电流情况下，工作温度的变化对激光器结电压噪音谱的影响．     

基于光纤过耦合器结构的温度应变传感器

从微纳光纤耦合的角度,采用单模光纤2×2耦合的方式,利用光纤过耦合设计出一种光纤传感器.通过改变光纤耦合器的拉锥参数使其达到过耦合状态,此时光纤自身的过耦合结构受环境影响导致光波长会对外界的温度和应变变化有较高的响应度,以此来实现对温度和应变的测量.实验中分别拉锥了过耦合长度为22000μm和22500μm的光纤过耦合...     

Improved photovoltaic effects in Mn-doped BiFeO_3 ferroelectric thin films through band gap engineering

As a low-bandgap ferroelectric material, BiFeO_3 has gained wide attention for the potential photovoltaic applications,since its photovoltaic effect in visible light range was reported in 2009. In the present work, Bi(Fe, Mn)O_3thin films are fabricated by pulsed laser deposition method, and the effects of Mn doping on the microstructure, optical, leakage,ferroelectric and photovoltaic characteristics of Bi(Fe, Mn)O_3 thin films are systematically investigated. The x-ray diffraction data indicate that Bi(Fe, Mn)O_3 thin films each have a rhombohedrally distorted perovskite structure. From the light absorption results, it follows that the band gap of Bi(Fe, Mn)O_3 thin films can be tuned by doping different amounts of Mn content. More importantly, photovoltaic measurement demonstrates that the short-circuit photocurrent density and the open-circuit voltage can both be remarkably improved through doping an appropriate amount of Mn content, leading to the fascinating fact that the maximum power output of ITO/BiFe_(0.7)Mn_(0.3)O_3/Nb-STO capacitor is about 175 times higher than that of ITO/BiFeO_3/Nb-STO capacitor. The improvement of photovoltaic response in Bi(Fe, Mn)O_3 thin film can be reasonably explained as being due to absorbing more visible light through bandgap engineering and maintaining the ferroelectric property at the same time.     

Improved adaptive-threshold burst assembly in optical burst switching networks

An improved adaptive-threshold burst assembly algorithm is proposed to alleviate the limitation of conven- tional assembly schemes on data loss and delay.The algorithm will adjust the values of assembly factors according to variant traffic regions.And the simulation results show that,by using the adaptive-factor adaptive assembly scheme,the performance of networks is extensively enhanced in terms of burst loss probability and average queuing delay.