气动CO_2激光器小信号增益的实验研究

用放大法测量了分别在甲苯和乙醇两种液体燃烧驱动下气动CO2 激光器的小信号增益系数。实验发现 ,用甲苯作为燃料时激光器的平均小信号增益系数可达 0 .62m- 1,远远高于乙醇作燃料时的小信号增益系数。结合甲苯和乙醇分别与空气燃烧后产物组分的配比 ,对实验结果进行了分析 ,得出甲苯是燃烧驱动气动CO2 激光器的一种比较理想的燃料     

气动CO2激光器小信号增益的实验研究

用放大法测量了分别在甲苯和乙醇两种液体燃烧驱动下气动CO2激光器的小信号增益系数。实验发现,用甲苯作为燃料时激光器的平均小信号增益系数可达0.62m-1,远远高于乙醇作燃料时的小信号增益系数。结合甲苯和乙醇分别与空气燃烧后产物组分的配比,对实验结果进行了分析,得出甲苯是燃烧驱动气动CO2激光器的一种比较理想的燃料。     

磷酸盐激光玻璃非激活吸收系数测量研究

介绍了高功率激光放大器系统中磷酸盐激光玻璃的静态透过率测量。在正常运行条件下,4片长按布儒斯特角放置的国产N31钕玻璃片对1.054um的激光波长平均静态透过率为94.5%,介质的损耗系数为0.294%cm-1,平均非激活吸收系数为0.146%cm-1。在此基础上对片状放大器的增益系数的测量结果进行了修正,获得了5.25%cm-1的小信号增益系数。     

一种新的光纤拉曼增益系数的测量方法

拉曼增益系数是描述拉曼散射的一个基本参数,通常用小信号增益法来测量,这种方法需要信号光,缺点是整个测试过程较长,易受到抽运光和信号光不稳定性的影响.文章提出一种新的测量方法,即利用光纤的受激拉曼谱和自发辐射谱的解调来获得光纤拉曼增益系数.测量了G.652光纤的增益系数,并与小信号增益法的测量结果进行了比较.     

电子束抽运氩离子准分子跃迁小信号增益的测量

对强流相对论电子束抽运氩产生的氩的第三谱带进行了研究。利用反射镜法对其小信号增益系数进行了测量。根据测量的实验装置和方法,建立了近距离探测的精确数学模型。综合运用数值分析方法对该模型进行了求解,得到了小信号增益系数。     

Na2第一三重态吸收系数及小信号增益系数测量

本文报导了Na2第一三重态跃迁吸收系数和小信号增益系数的测量。在整个第一三重态跃迁区域内,小信号增益系数大于吸收系数,证实了产生激光振荡的可能。     

使用可调谐LD激光作探针测量泛频HF化学激光器小信号增益

发展了一种使用可调谐ＬＤ激光为探针直接测量ＨＦ激光器小信号增益的方法。以计算机程控步进电机驱动ＬＤ激光器波长扫描,测量进入ＨＦ激光反应室和从反应室出射的探针光功率,并依此计算ＨＦ激光器小信号增益系数。实测ＨＦ激光器小信号增益系数最大值约５×１０－ ３ｃｍ －１ ,增益－ 波长半宽度约１－５ｎｍ ,增益时间半宽度０－５ｓ。对测量方法结果进行了讨论。     

利用参量放大效应测量光纤的非线性系数和色散参数

通过对理想条件下得出的光纤参量放大增益解析解和相位匹配关系表达式进行修正,得出在光纤有损耗 时,小信号峰值增益和光纤非线性系数成正比以及光纤色散参数和峰值增益波长与抽运光波长的差成反比两个近 似表达式。以此为基础提出:只要在直流抽运光作用下测出小信号峰值增益以及增益峰值波长与抽运波长之差, 然后通过简单的代数运算就可以得出光纤的非线性系数和色散参数。实验中,分别用两个不同波长的抽运光,对 一卷长度为1450m的高非线性色散平坦光纤(HNLF)的非线性系数和色散参数进行了测量。测得非线性系数为 γ=11.8W-1·km-1,色散斜率在1550nm附近为S=0.0157ps/(nm2·km)。其中,色散斜率测量值和商家给定的 值之间误差不超过5%。对在测量中抽运光和信号光之间由于拉曼放大作用所带来的增益谱不对称性进行了讨论。     

Nd:YAG激光器横模选择的实验研究

本文用简单的方法测量了Nd:YAG棒的热焦距和小信号增益系数;提出了Nd:YAG连续激光器选择基横模的有效设计方法,并对这种选模技术作了实验研究,最后从理论和实验上证实,采用平—平腔加小孔光阑选择基横模,必须根据热焦距和小信号增益系数正确设计谐振腔参数,否则加小孔光阑是徒劳无益的.     

光解碘原子激光器小信号增益测量

描述了利用光解碘原子激光器作为探测激光测量另一台光解碘激光器增益的装置和两台碘激光器的同步技术。讨论了压力对小信号增益系数的影响。     

Small-Signal Analysis and Crosstalk of Linear Optical Amplifiers

The small signal dynamic behavior of the linear optical amplifier (LOA) is described by using small signal analysis to evaluate both gain and rate equations. Analytical results are obtained for both horizontal and vertical emissions that delineate the difference between the LOA region of maximum gain and gain compression. Crosstalk is calculated by adding a second gain equation to represent the output in a parallel channel. The analytical approach is based on the representation of the laser gain with the concept of the frequency dependent stimulated lifetime. This model is especially useful to represent multiple channels in the LOA. Experimental data are found to be well matched by the calculated results.     

基于耦合电感高增益Buck-Boost变换器小信号建模

基于耦合电感的高增益变换器在新能源发电和直流微电网中均有良好的应用前景.论文在分析基于耦合电感的高增益升降压(Buck-Boost)变换器工作原理的基础上,采用开关流图法建立变换器的模型,详细推导了变换器的稳态模型和交流小信号模型;电力仿真(PSIM)软件对变换器小信号模型的仿真结果证明论文模型的正确性.论文结果对高增...     

基于GaN宽带管芯的X波段功放设计

本文在无大信号模型和静态I-V曲线下,应用小信号S参数,power tuned下的负载反射系数和线性模型,得到输出阻抗,应用宽带匹配进行阻抗设计。后加载偏置对S31进行仿真,并观测对S11的影响,从而保证扼流效果并且减小对匹配电路的影响。同时应用小信号S参数和输出阻抗得出输入阻抗,保证增益的平坦性。保证了在8-12GHz下,输出驻波VSWR〈1.4,偏置隔离大于-30dB,小信号增益12.75dB,带内波动0.5dB。     

Noise Temperature Characteristics and Gain-control of Avalanche Photodiodes for Laser Radar

Avalanche photodiodes（APDs） are promising light sensors with high quantum efficiency and low noise. It has been extensively used in radiation detection, laser radar and other weak signal detection fields. Unlike other photodiodes, APD is a very sensitive light detector with very high internal gain. The basic theory shows that the gain of APD is related to the temperature. The internal gain fluctuates with the variation of temperature. Investigated was the influence of the variation of the gain induced by the fluctuation of temperature on the output from APD for a very weak laser pulse input in laser radar. An active reverse-biased voltage compensation method is used to stabilize the gain of APD. An APD model is setup to simulate the detection of light pulse signal. The avalanche process, various noises and temperature＇s effect are all included in the model. Our results show that for the detection of weak light signal such as in laser radar, even a very small fluctuation of temperature could cause a great effect on APD＇s gain. The results show that the signal-tonoise ratio of the APD＇s output could be improved effectively with the active gain-control system.     

Radio Propagation Model Considering Antenna Beam Tilt with Application to Small Cells

Antenna beam tilting techniques are commonly used to deploy small cells with reduced coverage compared than macrocells. This paper proposes a new statistical propagation model for small cells with electrical and mechanical antenna tilt. The proposed model combines the dual slope path loss model with the departure angle spread model for considering antenna beam tilt. The proposed departure angle spread model introduces a new parameter reflecting the azimuth spread of departure (ASD) angles in order to account for the change of transmit antenna gain by electrical and mechanical tilt. Through this approach, the antenna gain for each ray is separately computed by considering the transmit antenna beam pattern as well as the antenna beam tilt. We perform field tests to measure the receive signal power in the downlink of commercial Long-Term Evolution small cells with antenna tilt. Based on the measurement data, we find the statistically optimal ASD parameter using a grid search and calculate the antenna gain for each ray. Also, the overall transmit antenna gain is obtained by averaging antenna gains for multiple rays. To assess the accuracy of the proposed model, the estimation error is evaluated by comparing the measured receive signal power with the estimated value using a propagation model, and the performance of the proposed propagation model is compared with those of existing path loss models in terms of root mean square error deviation. Then, it is shown that the proposed model provides more accurate propagation estimation for small cells than existing models.     

氧碘化学激光器射流数值模拟方法研究

为了研究氧碘化学激光器喷流流场流动情况,采用数值方法求解二维可压缩非定常Navier-Stokes方程及组分连续方程,空间离散格式为AUSM+up格式,用四步龙格-库塔方法作显式时间推进,湍流粘性系数使用k-ε两方程湍流模型进行求解。假设混合气体为热力学完全而热值非完全气体,化学反应模型采用有限速率反应模型。使用一种松弛迭代的方法来处理化学源项的刚性问题。计算了一个标准算例,结果与美国GASP程序计算结果符合良好。对氧碘化学激光器流场进行了二维数值模拟,研究了该激光器中激发态氧初始产额、水蒸气含量以及不同喷管数目对增益分布的影响。结果表明,除水和增加激发态氧初始产额都可使小信号平均增益增大,采用两个碘喷管比采用一个碘喷管能够获得更大的小信号平均增益。     

扩散型连续波HF化学激光器小信号增益的计算

应用层流边界层二维简化模型计算了扩散型连续波HF化学激光器的小信号增益。研究了气流速度、温度、组份对增益的影响,得到一些有用的结果。计算结果与二维Navier-Stokes方程组的计算结果相符,但计算方法较简单。     

Theoretical demonstration for signal gain in multiple four-wave mixing processes based on cubic susceptibility medium

An insight into the signal gain in multiple four-wave mixing (MFWM) processes based on a cubic susceptibility medium is theoretically proposed and demonstrated. A dual-pumped fiber optical parametric amplification (FOPA) model is developed with the exact expressions for the signal gain and its 3-dB bandwidth successfully yielded. With these analytical expressions, we show that when pump-1 and pump-2 wavelengths tuned at 1549 and 1551.02nm, the 3-dB bandwidth of the signal gain can be achieved at about 2253.4nm theoretically by properly setting the pumped powers. Numerical simulations show that there is a small pinnacle emerging in the signal gain spectrum owing to the degenerate OPA process occurring. The proposed OPA model can find potential applications in all-optical wavelength conversion, optical amplifier, and all-optical sampling.     

主喷管总温对MGDL小信号增益系数的影响

在国内外数值模拟工作的基础上,建立了更加准确的"混合型气动CO2激光器(简称MGDL)"增益场计算程序。利用该程序,一方面研究了基于筛形喷管的混合型气动CO2激光器光腔中的小信号增益分布规律;另一方面着重研究了主喷管入口总温对基于筛形喷管的混合型气动CO2激光器小信号增益系数的影响规律。计算结果表明:当其他参数不变时,主喷管入口总温存在一个最佳值,使得光腔中的小信号增益系数最大;当主喷管入口总温小于这个最佳值时,随着主喷管入口总温的增加,光腔中相同位置处的小信号增益系数逐渐增大;当主喷管入口总温大于这个最佳值时,随着主喷管入口总温的增加,光腔中相同位置处的小信号增益系数逐渐减小。此外,分析了主喷管入口总温对小信号增益系数的影响机制。