Self-stabilized nonlinear lateral modes of broad area lasers

The lateral modes of broad area lasers are investigated theoretically. The nonlinear interaction between optical field and effective refractive index leads to a saturable nonlinearity in the governing field equation, so that self-modulated solutions are found to be stable with increased current injection above saturation intensity. We derive approximate analytical solutions for traveling wave fields within the broad area laser. The field amplitude consists of a small ripple superimposed on a large dc value. Matching fields at the boundary determines the modulation depth and imparts an overall phase curvature to the traveling wave mode. There are multiple lateral modes for a given set of operating conditions, and modes with successively more lobes in the ripple have greater overall phase curvature. In contrast to the linear problem, several lateral modes can achieve the same modal gain, for a given injected current density, by saturating the gain to different extent. Thus, these modes would exhibit slightly different optical powers.     

激光跟踪测距仪在体育领域中的应用

介绍了激光的特点及激光跟踪测距仪的工作原理 ,在此基础上 ,设计了一种激光跟踪测距系统 ,对该系统的组成及主要部件进行了阐述 ,给出了该系统的主要性能数据 ,并对该系统在体育领域中的应用前景作了展望。     

Multitemporal passive microwave mapping in MACHYDRO'90

MACHYDR0'90 was an experiment conducted in Pennsylvania in 1990 to study the synergistic use of remote sensors in multitemporal hydrologic studies. As part of this mission the pushbroom microwave radiometer was flown and used to produce brightness temperature maps. Verification studies and vegetation algorithms for mixed land cover areas are described     

Parkinson's disease. Second of two parts

At no time in the past have the basic and clinical sciences applied to Parkinson's disease been so active. Experimental therapies under study at present promise to improve on the limitations of existing treatments. Future progress in understanding the causation and pathogenesis of the disorder will permit the development of new treatments that will slow, halt, or even reverse the currently inexorable progressive course of Parkinson's disease.     

PWM整流器高功率因数的实现

论述了交流斩波电路中控制部分的工作原理，并对该电路中电抗器的取值进行了计算。采用16位80C196KC单片机能使控制电路非常简单，并容易实现高频开关器件整流器的高功率因数。     

PD雷达欺骗干扰方法浅析

概要介绍了PD雷达的抗干扰性能及其特点．并主要对PD雷达的欺骗干扰方法进行了一定的讨论。     

Ce3+离子对掺Er3+碲酸盐玻璃光谱性质的影响

研究了Ce3 + 对掺Er碲酸盐玻璃荧光光谱性质的影响 ,比较了不同的Ce3 + 掺杂浓度下Er3 + 离子荧光发光强度的变化 ,分析了Ce3 + 离子对Er3 + 离子作用的原理 ,应用经典方程计算了Er3 + 离子 4I1 1 / 2 能级的荧光寿命及其变化     

An optimum parallel architecture for high-speed real-time digital signal processing

The authors describe a parallel processing architecture for real-time digital signal processing that has demonstrated virtually 100% data processing efficiency in a number of areas. The Teamed-Architecture Signal Processor (T-ASP) is a field-proven, commercially available optimal system solution to the extremely high computational and I/O rates encountered in modern digital-signal-processing environments. The design of T-ASP involves the consideration and implementation of many architectural concepts used to enhance the performance of a computer, including programmability, parallel processing, vector processing and pipelining, memory interleaving, double cache memories, multiple high-speed I/O interfaces, and segmentation of the processors for elimination of both CPU and data-handling overhead. The authors discuss hardware architecture design and implementation; hardware management; and software architecture design and implementation.<>     

CdSe量子点的制备与荧光特性研究

主要讨论了CdSe量子点的制备及荧光特性。CdSe量子点由化学方法制备，通过选择不同的反应时间得到不同尺度的量子点样品。用荧光方法研究了量子点样品在石英衬底和有机溶剂中的荧光特性。实验表明，这些量子点都有良好的荧光特性。还用无限深球方势阱模型分析了量子点样品的电子态，并根据荧光参数估算了量子点的尺度．各样品荧光峰具有一致的半峰宽，表明CdSe量子点的成核过程在反应开始时同时完成。     

预应力锚固技术在龙滩水电站高边坡工程中的应用

龙滩水电站进水口高边坡最大坡高达420m，为保证高边坡的稳定，采用预应力锚索技术。预应力锚索的加固作用非常明显，不仅为边坡的稳定提供了经济、有效的手段，而且为按期截流创造了条件。