外电场作用下红外光折变GaAs的双光束耦合增强效应

报道了立方晶体GaAs:Cr在外电场作用下的红外光折交增强效应,着重分析双光束耦合过程中空间电荷电场幅度和位相的空间分布变化情况。计算结果很好地解释了实验测量结果。     

GaAs光折变晶体中的双光束正交偏振耦合

本文报道利用红外1.15μm He-Ne激光在光析变晶体GaAs:Cr中进行双光束耦合的理论和实验研究,在双光束同向传播耦合时,我们推得了耦合方程的解,在GaAs立方晶体的电磁波耦合中分别仔细考虑了垂直与平行于入射面的偏振情况。     

红外光折变GaAs中的双光束耦合

报道用1.15μm红外He-Ne激光器在光折变晶体GaAs:Cr中进行相对传播双光束耦合的实验研究,给出了衍射效率和增益系数随二束光的总光强和二束光的光强比变化的实验结果。     

GaAs双光束耦合中的普克尔效应

本文报道在GaAs晶体中用1.15μm红外He—Ne激光进行相对传播的双光束耦合的实验研究,测量了透射光束偏振面的旋转角(?)与两束光强比β_0的关系,这些现象可归结于光感空间电荷电场引起的线性电光效应(普克尔效应)所造成。     

光折变立方晶体中的双光束正交耦合

本文报导光折变立方晶体中的双光束耦合的理论分析和实验研究,讨论了具有闪锌矿结构和具有非中心对称的43m立方晶体中的双光耦合,立方晶体具有(ε_w)_(ij)=n~2δ_j和非零电光系数的张量元γ_(ijk)=γ_(kij)=γ_(41)因此,由相干光场激发的载流子通过漂移和扩散产生空间电荷和电场,又通过线性电光效应(普克尔效应)形成折射率或电介常数空间变化的相位光枷     

光折变晶体中双光束耦合时间响应特性的研究

从描述双光束耦合规律的动态方程组出发．在考虑了光栅调制度变化后，给出了包含晶体固有参数、入射总光强、入射夹角、光强比等变量在内的写入响应时间解析表达式，实验结果与理论分析定性符合很好。     

在红外GaAs光折变晶体中透射和衍射光束的空间相互作用

给出用1.15μm红外He-Ne激光在光折变GaAs晶体中进行相对传播双光束耦合的理论和实验研究,透射和衍射光束偏振态空间相互作用的交流分量具有Sin2φ的函数形式,结果表明理论与实验符合很好.     

光擦除双光束耦合的温度特性

建立了光擦了作双光束耦合理论的简单模型，引入了响应强度概念及描述参量，数值计算了响应强度的温度特性，对Ｃｅ：ＫＮＳＢＮ晶体给出了光擦除双光束耦合温度特性的实验结果。     

Space Charge Observation in Aramid/Epoxy Insulations Under DC Electric Fields

With the progress of printed circuit technology, the reliability of bulk insulation has become important, as well as that of surface insulation, particularly in multilayer boards and embedded boards. We observed the space charge behavior of various insulating materials used in printed circuit boards, and found that internal charges move in aramid/epoxy specimens under dc electric fields. The electric field near the surface of the specimen, therefore, was increased to have more than twice the strength of the average applied field. The space charge profile was influenced by the internal structure, and its formation was accelerated by the increase of temperature. Since the space charge profile affects the internal electric field distribution, the internal charge behavior should be examined with respect to the design of the insulation of a printed circuit board.     

光折变Bi12TiO20晶体中的波耦合性质

研究了光折变Bi12TiO20(TBO)晶体中的二波耦合矢量特性.对扩散记录全息求得信号光能量增益和偏振态改变的分析解,研究它们在3种制备可得的晶体切割面上随入射抽运光和信号光(不同)偏振方向、光栅取向以及晶体厚度的变化关系,并给出在任意光栅取向的取值范围.分析了信号光能量增益和偏振态改变量分别达到最大值时各向同性和各向异性耦合的作用,并研究旋光、压电及弹光效应在3种晶体切割面上对矢量波耦合的影响.     

Investigation of Built-in Electric Fields at the GaSe/GaAs Interface by Photoreflectance Spectroscopy

Semiconductors - Built-in electric fields appear during the molecular-beam epitaxy of GaSe on a GaAs(001) substrate at the GaSe/GaAs interface, the presence of the fields is evidenced by...     

High-Voltage Electric Field Coupling to Humans Using Moment Method Techniques

With the advent of EHV transmission lines and the almost certain possibility of UHV lines, it becomes increasingly important to describe accurately the transmission line electromagnetic field interaction with life forms. This paper develops a numerical method for predicting current and normal electric field distributions induced on humans situated in the near vicinity of the lines. The technique is based on the method of moments in which the human body is modeled as a collection of straight cylindrical segments with lengths and radii comparable to that section of the body being modeled. Various scenarios are considered, eg., a well-insulated person standing on the ground beneath the transmission line; an individual in good contact with the earth; or a lineman working in very close proximity to an energized conductor. The position of the arms is varied; for example, arms extended or down at the side. The question of biological hazards from exposure to fields of these systems is also discussed.     

Photorefractive determination of the sign of photocarriers in InP and GaAs

The sign of the majority photocarriers in semi-insulating iron-doped InP and undoped GaAs containing EL2 centres illuminated at 1.06 ?m is unambiguously determined from the direction of beam coupling in a two-wave photorefractive mixing experiment previously applied to ferroelectric crystals. Majority photocarriers in these InP:Fe and GaAs:EL2 crystals are found to be electrons.     

A Multiple-Device Cavity Oscillator Using Both Magnetic and Electric Coupling Mechanisms

This paper presents a novel concept to increase the number of active devices combined in a cavity oscillator by coupling them to both electric and magnetic fields inside the cavity. The structure employs probes and coaxial lines for electric and magnetic coupling, respectively. The sum of the output powers from individual devices combined can be obtained by properly adjusting the coupling factors of the circuit. Operation principles of the circuit are analyzed for probe coupling, and results are applied to explain the operation of the circuit when both probe and coaxial coupling are used. The circuits described here are free from moding instabilities. Prototype circuits have been constructed at X-band, using Gunn diodes, for experimental confirmation of the theory developed.     

外加电场作用下光折变晶体的各向异性自衍射

对于晶体ｃ轴平行于入射面的实验配置，观察到了掺杂钾钠铌酸锶钡（ＫＮＳＢＮ）晶体在外加电场作用下的各向异性自衍射现象；同时给出了包含光栅波矢空间分布和空间电荷场二阶分量作用的各向异性自衍射的耦合波方程及其数值解，理论分析和实验结果都表明各向异性自衍射光来自于两束入射光的共同作用