Comparison of 1300 nm quantum well lasers using different material systems

The band structure and material gain are calculated for 1300-nm band quantum well lasers of GaInNAs, AlGaInAs and GaInAsP material systems. The material compositions for each system are carefully chosen for comparison. The calculated results show that the peak gain is around the same in spite of the difference in band structures for the three systems.     

Integrated Front-End Receiver for a Portable Ultrasonic System

This paper concerns the design, the implementation and the validation of a fully integrated front-end receiver for a portable ultrasonic system. This front-end receiver includes a logarithmic preamplification circuit and followed by a programmable-gain compensator. The proposed building blocks largely amplify small amplitude signals, and moderately the large amplitude ones. They also compensate signal attenuation due to its traveling of several human body tissues. The ultrasonic receiver is implemented in CMOS 0.35 m technology. Spectre simulations of the front-end receiver show unity gain bandwidth higher than 100 MHz when driving a load of 1 pF. The expected measurements of the fabricated chip are reported. This chip operates at 3.3 V supply voltages, while maintaining wide common mode rejection ratio, high gain and low input offset voltage. The total power consumption is 15.6 mW and the total chip area is 7.2 mm² including the digital part needed to program the TGC.     

采用超强FEC技术的160 km无中继传输

文章首先介绍了超强前向纠错(SFEC)技术的基本原理, 并利用该技术在G.655光纤上实现了传输容量40×10 Gbit/s,单跨段长度160 km,线路衰耗44 dB的无误码传输实验.最后,给出了实验结果,各项实验结果均满足中国通信行业标准要求.     

A New Type of Digital Compensatory Millimeter Wave Radiometer

System gain and receiver noise are two main impact factors of total power millimeter wave (MMW) radiometer output. In this paper, a new method of using software to compensate system gain and receiver noise fluctuation is introduced. This method can keep the long-term stability and accuracy of the radiometer. At the same time, only one matching load is used as the reference source, which can prevent the trouble caused by using two cold and hot calibration sources in ground-based or airborne radiometer. The preliminary experiment proves the efficiency of the method.     

CMOS集成混频器噪声模型的计算机仿真与分析

根据Hspice仿真结果，分析了CMOS集成混频器中场效应管的闪烁噪声和寄生电容产生输出噪声的详细过程。通过改变电路仿真参数，得出相应的仿真数据，结合理论模型对实验数据进行了分析。结果表明，由闪烁噪声引起的直接开关噪声增益随本振幅度递减，由寄生电容引起的间接开关噪声增益随寄生电容值和本振频率递增。     

Emission spectra and stimulated emission characteristics of [N2]2--N2 molecular dimer

It has been proved by ab initio calculation and theoretical analysis that there exist [N2]2--N2 molecular dimers with D2h symmetry group, and there also exists an electric dipole excimer-like transition a1B2g→a1B3u. The theoretical spectra accord with the experimental results for transition a1B2g→a1B3u. The stimulated emission characteristic of N2 molecular dimer was researched through the microwave excited highly pure nitrogen and the method of amplified spontaneous emission. The experimental results show that N2 molecular dimer has stimulated emission characteristics when the microwave power is more than 100 W and the N2 pressure is in the range from 260 Pa to 2200 Pa.     

掺铒光纤放大器

阐述掺铒光纤放大器(EDFA)的原理和结构，介绍掺铒光纤放大器在密集波分复用(DWDM)传输系统中的应用，掺铒光纤放大器的优缺点以及发展前景。     

高增益激光的饱和效应和最佳输出耦合

本文在均匀和非均匀谱线加宽情况下,计算了高增益介质在不同小信号增益系数和吸收系数下的激光输出特性,并讨论了饱和效应和最佳输出耦合。     

类氖锗X光激光增益实验

本文介绍了在LF-12激光器上进行的类氖锗X光激光增益实验。当泵浦激光波长为1.053μm,脉宽为1.1～1.4ns、能量为550～650J、线聚焦焦斑为185μm×20mm时,使用片状锗靶测量波长为19.61、23.22、23.63、24.73及28.65nm的五条激光跃迁线的增益分别为3.06、3.99、3.72、2.36及4.59cm^(-1)。实验给出了关于柱形等离子体激光介质发射区厚度及软X射线激光发射角的实验数据。实验也给出了软X射线激光强度随泵浦激光功率密度变化的讯息。最后分析了由薄膜锗X光激光靶进行的增益实验中未看到激光增益线的原因。     

群论在H2分子受激喇曼散射中的应用

本文利用U(4)群代数描述双原子分子振转谱的对称性质,利用群论计算了H_2分子受激喇曼散射跃迁矩阵元,绘出了受喇曼散射的截面与增益系数,较好地与实验结果符合.