The effects of a detuned optical input on bistable laser diodeswith inhomogeneous current injection

The effects of an external optical input on a bistable laser diode (BLD) with inhomogeneous current injection are discussed. The bistable behavior of optical output versus injection current is shown to be variously modified, depending on the wavelength and power of the optical input. Optical set and reset operations and optical logic achieved by optical input pulses can be explained by these characteristics of a BLD modified by an external optical signal. Analysis using rate equations is also offered to help interpretation of experimental results, as well as the optical output and the bias current injected into the BLD     

Circuit modeling of multimode bistable laser diodes

A circuit model for multimode bistable laser diodes (BLD) has been developed from the rate equations. The model is simulated for dc sweep and transient conditions using circuit simulation program PSPICE. The hysteresis behaviour and the dynamic properties of the longitudinal modes of the BLD are studied. The dc sweep simulation shows “S”-shaped bistability for the fundamental mode, whereas the sidemodes exhibit a “loop”-like bistability. The transient simulation also shows similar behaviour     

Multimode interference bistable laser diode

We propose a novel bistable laser diode (BLD) with active multimode interference (MMI) cavity. Bistable switching can be realized between two cross-coupled modes by means of gain saturation. Static characteristics of the multimode interference (MMI)-BLD are analyzed using a finite-difference beam propagation method. The photon-carrier interactions are calculated using the carrier-rate equation. This model gives accurate distributions of photon and carrier densities, optical gain, and refractive index inside the cavity. We predict that the MMI-BLD shows bistable switching between the two cross-coupled modes by light injection, therefore allowing it to be used as all-optical flip-flop or optical memory.     

新型低驱动电压电子纸显示单元的研究

研制了一种基于介质上电润湿(electrowetting-on-dielectric,EWOD)的新型低驱动电压电子纸反射式显示单元器件.本文分析了器件的工作原理以及性能影响因素,并提出用优化的氮化硅与碳氟聚合物复合介质层来改善器件的驱动电压.实验证实,器件在15V低电压驱动下成功实现了"开启"、"关闭"功能,其"开启"、"关闭"响应时间小于1/30s.     

All-optical set-reset operation of a bistable semiconductor laserintracavity-coupled to a vertical-cavity surface-emitting laser

We experimentally demonstrate a bistable laser diode (BLD) formed by a vertical-cavity surface-emitting laser (VCSEL) coupled to an in-plane laser (IPL) that includes a saturable absorber section. The device can be switched between its two states (corresponding to either the in-plane laser or the vertical-cavity laser being on) by injection of optical pulses. We also discuss possible applications for this device     

精确紫外辐射定标中的稳功率光源系统

简述了精确紫外辐射定标中光源的选择,介绍了影响光源系统稳定性的因素及其解决方法,并着重讨论了稳功率光源系统的硬件实现方法.该硬件电路分为模拟电路和数字电路两大部分,主要采用三端稳压技术和单片机控制技术,不仅为光源提供了稳定的动力电源,还进一步利用光反馈电路更好地保证了光输出的稳定.实验结果表明,带有光反馈的恒压恒流直流电源发光稳定,为精确紫外辐射定标提供了高稳定度的紫外光源.     

埋层低掺杂漏SOI高压器件的击穿电压

提出一种具有埋层低掺杂漏(BLD)SOI高压器件新结构。其机理是埋层附加电场调制耐压层电场,使漂移区电荷共享效应增强,降低沟道边缘电场,在漂移区中部产生新的电场峰。埋层电中性作用增加漂移区优化掺杂浓度,导通电阻降低;低掺杂漏区在漏极附近形成缓冲层,改善漏极击穿特性。借助二维半导体仿真器MEDICI,研究漂移区浓度和厚度对击穿电压的影响,获得改善击穿电压和导通电阻折中关系的途径。在器件参数优化理论的指导下,成功研制了700V的SOI高压器件。结果表明:BLD SOI结构击穿电压由均匀漂移区器件的204V提高到275V,比导通电阻下降25%。     

一种新颖的自反馈光注入单频窄线宽光纤激光器

报道一种基于自反馈光注入的单频窄线宽光纤激光器。激光器采用线形腔结构,用高掺杂Er3+光纤作为增益介质,利用输出信号光分束反馈与腔内振荡激光干涉,形成折射率光栅与增益光栅共同作用选择纵模,获得稳定的1 549.85 nm单频窄线宽激光输出。在975 nm单模激光二极管(LD)抽运下,激光器的抽运阈值光功率为13 mW。当抽运光功率为112 mW时,最大输出信号光功率为30.6 mW,对应的光-光转换效率为27.3%,斜率效率为30.2%,信噪比大于50 dB。采用延时自外差方法测量线宽,当使用30 km单模光纤延迟线时,测量得到激光器的3 dB线宽为4.0 kHz。     

Instability of semiconductor lasers due to optical feedback from distant reflectors

We explain an istability occurring in continuously operating lasers due to moderate feedback from distant reflectors. This instability occurs despite the fact that the laser is stable with respect to small deviations from steady-state operation. It is the result of finite phase and carrier number changes caused by fluctuations in spontaneous emission. We predict several properties that agree with recent experimental observations: 1) the instability only occurs when the laser reaches a steady state that maximizes coherent feedback and laser light intensity; 2) the instability vanishes at strong feedback levels; and 3) at moderate feedback levels, the laser will be nearly stable at threshold, but unstable when operated well above threshold. The latter behavior results in a nonlinear "kinked" shape in the light versus current relation.     

一种功率可调的稳定激光光源的实现方法

在光纤通信系统测试中,波长为850 nm、 1310 nm、1490 nm、1550 nm和1625 nm 等的红外激光光源作为信号源具有广泛的应用。该光源需要 具有稳定的输出光功率。通常采用含有衰减片的光 衰减器对其输出光功率进行调节以满足不同场合的测 试与校准需求。通过分析激光器输出功率与 驱动电流的特征曲线,提出了一种在电路上采用压控电 流的方法,实现了稳定光源的输出光功率步进可调(调 节范围为30 dB)。该方法可有效减少光衰减器的使用,缩减测 试系统的仪器数量,提高测试效率,降低测试成本。     

The current injection method for AC plasma display panel (PDP) sustainer

A new concept of energy recovery for a plasma display panel (PDP) is proposed. Different from conventional LC resonant sustaining drivers, the current built up before inverting the polarity of the panel electrodes is utilized to change the panel polarity together with energy previously charged in panel capacitance. This operation provides zero-voltage switching of switches and reduction of electromagnetic interference by rejecting the surge current when the sustain switches are turned on. The buildup current helps to reduce the transition time of the panel polarity and may produce more stable light waveforms. This method is suitable for a PDP sustaining driver requiring stable light emission characteristic while it maintains low circuit loss like the series-resonant-type energy recovery circuit which is known to be a very effective method.     

基于单片机的可见光及紫外光强探测系统

BH750FVI是一种具有I2C总线接口的环境光强探测芯片,UVM-30是一种具有线性电压输出的紫外线探测模块.几乎不需要其他外围电路,采用这两种器件就可以与单片机构成一种涵盖从紫外到可见光的光强探测系统.本文详细介绍了这两种探测器的性能特点及其与单片机STC12C5608AD的连接方式;给出了单片机对这两种探测器的控制、光强数据的获取、以及数据显示等方法.采用具有数字接口或规格化输出的探测器构成的测量系统,结构紧凑,可靠性和稳定性都很高.     

Analysis of Interactions Between Central and Vagal Respiratory Control Mechanisms in Cats

In anesthetized cats, regulation of the duration of inspiration (Ti) and expiration (Te) has been investigated by analyzing the operation of central inspiratory on-and off-switch mechanisms. Using the tracheal pressure (P) generated during airway occlusion at FRC as a measure of central inspiratory activity, and the end-inspiratory pressure (P0ax) as the setting of the off-switch threshold, we considered two indices in the central and lung volume-related control of Ti: (a) P/P0max, an index of central inspiratory contribution to inspiratory off-switching, and (b) 1?P/P0 max' an index of the additional vagal input needed to terminate inspiration. Both indices were found to be independent of PaCO2, varying solely as a function of time from the onset of inspiration. Changes in the relationship between tidal volume (VT) and Ti with variation in body temperature and unilateral vagotomy were attributed to separate effects on the 1?P/P0max vs Ti and 1?P/P0max vs VT relations, respectively. The rapid shallow breathing pattern observed with continuous negative pressure breathing has been explained on the basis of early activation of an inspiratory on-switch mechanism by lung deflation receptors.     

Enhancement of light extraction of green top-emitting organic light-emitting diodes with refractive index gradually changed coupling layers

By means of refractive index gradually changed coupling layers, a highly efficient green top-emitting OLED (TOLED) with enhanced light coupling efficiency and stable colors over angles has been realized. The refractive index transition of the coupling layers including the doping layer smoothes light extraction from the semitransparent cathode metal to the air, which is the reason for the enhancement of light coupling efficiency. The doping layer in the coupling layers also acts as a microparticle diffuser to eliminate the shift in EL spectra with viewing angles. A universal simulation has also been carried out, and the result suggests that the light coupling efficiency will be enhanced further if the refractive index transition of the coupling layers is continuous.     

一种半导体激光器自动控制系统的设计

根据半导体激光器的工作原理, 使用两片AVR单片机ATMEGA16作为核心控制部件, 并配合触摸屏式人机控制界面和外部硬件电路, 实现了半导体激光器功率稳定输出的自动控制系统。该系统包括恒流源、光功率采样反馈、保护电路、温度控制等部分, 能为半导体激光器提供稳定、准确的驱动电流, 自动光功率控制和恒温控制。     

光纤通信中偏振光消光比测量方法的研究

本文对比了光纤通信系统中偏振光消光比特性参数的两种测量方法:旋转偏振器测量法和庞加莱球测量法.旋转偏振器法是通过用高速旋转的起偏器获取所需光功率来实现消光比的直接测量的;庞加莱球法则是根据偏振光的斯托克斯分量间接计算消光比的.前者的物理特性及原理直观,易于操作,但测量不稳定,且对传输波长有一定依赖性;后者物理特性相对抽象,系统相对复杂,但稳定性较高.     

基于STC单片机的智能灯控系统设计

针对目前众多公共场所照明用电浪费严重的问题,设计了一套基于STC单片机的智能灯控系统。人体红外热释传感器和可见光照度传感器采集的数据,通过单片机处理后向照明灯驱动电路发送相应信号,控制照明灯的开关和亮度。本系统具有成本低、运行稳定及智能化的特点。对提高用电效率、节能环保有很大帮助,应用前景广阔。     

Noninvasive pulse oximetry utilizing skin reflectancephotoplethysmography

The major concern in developing a sensor for reflectance pulse oximetry is the ability to measure large and stable photoplethysmograms from light which is backscattered from the skin. Utilizing a prototype optical reflectance sensor, locally heating the skin is shown to increase the pulsatile component of the reflected photoplethysmograms. Additional improvements to signal-to-noise ratio were achieved by increasing the active area of the photodetector and optimizing the separation distance between the light source and photodetector. The results from a series of in vivo studies to evaluate a prototype skin-reflectance pulse oximeter in humans are presented     

横向非周期性调制Kerr介质中的空间光孤子

数值方法研究了横向非周期调制Kerr介质中所支持的空间光孤子。数值模拟结果显示研究模型存在三种类型空间光孤子：低功率下的双峰孤子、高功率下的基本孤子和稳定传输的双极孤子。应用线性稳定性分析方法研究了三种类型空间光孤子的稳定传输的稳定谱,总结出三种类型光孤子稳定传输的条件。     

基于CPT原子钟的VCSEL激光器控制系统设计

设计基于原子相干布居俘获原理(CPT)的原子钟系统中垂直腔面发射激光器(VCSEL)控制器,其包括20 mA量程、低噪声、精密直流稳流电源、介绍VCSEL控制系统组成和工作原理,并时VCSEL激光器系统进行了测试分析.结果表明.该控制系统可以实现单模态、窄线宽及低功耗稳定光源,对CPT原子钟VCSEL光源应用具有参考和使用价值.