半导体激光双稳态光信号放大和处理

利用光纤耦合输出反馈泵浦半导体激光双稳装置,实现了微分增益、双稳和零偏等三种工作模式的运转。由此完成了恒定偏置和脉冲偏置光信号放大、光脉宽压缩、限幅、整形和开关等多种光信号处理功能。光信号增益达22.5dB,脉宽可压缩25倍。     

双稳态光信号放大器

利用氦氖-铌酸锂混合无镜双稳态装置实现了恒定光偏置和脉冲光偏置两种方式下的光信号放大,放大倍数分别达15和20—95。脉冲偏置下还观察到光信号放大同时伴随着信号脉冲波形的改善,     

光参量啁啾脉冲过饱和放大实现超短脉冲的频谱整形

光参量啁啾脉冲放大(OPCPA)非线性过程是个可逆过程,信号光增大到最大值时抽运光能量已几乎被耗尽,随即进入过饱和放大阶段,能量会由信号光和闲频光重新回到抽运光中.提出了利用这一过程实现啁啾脉冲频谱整形的一种新方法.通过数值模拟说明了这种啁啾脉冲频谱整形方法的原理.计算结果也表明了通过改变抽运光强、调节相位匹配角、改变抽运脉冲波形能实现对脉冲频谱整形结果的有效控制,甚至可以通过选择适当的抽运光和信号光的同步关系,使放大后输出信号光有一定的频移,这一点可以用来抑制钛宝石饱和放大引起的光谱红移.     

BBO Ⅱ类共线相位匹配结构中群速失配的补偿

为了消除群速失配对飞秒光参量放大(OPA)的不利影响，描述了在Ⅱ类共线相位匹配的飞秒BBO光参量放大中，同时倾斜抽运光和信号光的脉冲波面完全补偿三波群速失配的方法。理论计算了三波群速匹配时，相位匹配角、抽运光和信号光的脉冲波面倾斜角随信号光波长的变化。并分析了三波群速匹配对抽运光光斑尺寸的要求和对参量带宽的影响。结果表明，利用该方法不仅能够完全补偿飞秒BBO光参量放大在连续调谐时三波的群速失配，而且能够实现最大的参量带宽。此外，选取合适的抽运光光斑尺寸对提高参量增益至关重要。     

1kHz全光纤双程结构掺Yb3+脉冲光纤放大器

以1KHz低重复频率的脉冲激光为信号光源,实验研究了全光纤双程结构的脉冲光纤放大器.利用光纤声光调制器(AOM)滤除了放大过程产生的放大自发辐射光(ASE),并测量了该ASE功率;分析了低重复频率及双程结构对放大器输出特性的影响;研究了抽运光功率对输出脉冲宽度和脉冲峰值功率的影响.在注入信号激光波长1060nm、脉冲宽度10.2ns、峰值功率0.58W时,获得放大脉冲激光的脉冲宽度7.9ns、峰值功率245.2W,对应增益26.3dB.     

飞秒脉冲光参量中的色散和高阶非线性效应研究

通过数值模拟超强超短激光脉冲泵浦下的MgO:LiNbO3晶体的光参量放大过程,讨论了群速度色散和高阶非线性效应对能量转换效率和脉冲波形的影响。结果表明,群速度色散会使泵浦光脉宽增加,功率密度降低;同时,大功率泵浦下高阶非线性效应的影响不可忽略,它会进一步减小能量转换效率,还会使信号光的频谱展宽。为了提高单位晶体长度的参量放大增益,可以通过引入初始啁啾来抵消群速度色散的影响。     

色散和高阶非线性对飞秒光参变放大的影响

群速度色散和高阶非线性效应是影响超强超短脉冲抽运下光参变放大能量转换效率的重要因素.为了提高光参变放大的能量转换效率,采用理论分析和数值计算的方法,模拟超强超短激光脉冲抽运下MgO:LiNbO3晶体中的光参变放大过程,得到了不同抽运功率密度、不同群速度色散条件下光参变放大的能量转换效率曲线,并且讨论了高阶非线性效应对和脉冲时间波形和频谱的影响.结果表明,群速度色散会使抽运光脉宽增加,功率密度降低;大功率密度抽运下高阶非线性效应的影响不可忽略,它会进一步减小能量转换效率,还会使信号光的频谱展宽,为了提高单位晶体长度的参变放大增益,可以通过引入初始啁啾来抵消群速度色散的影响.     

飞秒光参量放大技术原理及应用

飞秒光参量放大技术是一种获得宽带飞秒脉冲的有效手段.首先介绍了飞秒光参量放大技术的基本原理,并通过数值模拟显示了群速度失配及位相失配对信号转换过程的影响.数值计算结果表明:群速度失配及位相失配会导致转换效率下降,群速度失配还会导致脉冲发生畸变.其次,综述了该技术在超短脉冲特别是周期量级脉冲产生方面的研究进展,并介绍了Baltuska等设计的可以产生3.9 fs脉冲的非共线光参量放大装置.其中,详细讨论了超连续白光注入源、泵浦光角色散以及晶体选择三方面内容.最后介绍了该技术在高能飞秒脉冲产生方面取得的最新研究进展.     

基于YCOB晶体分析信号光脉冲时间特性对光参变啁啾脉冲放大光谱和转换效率的影响

基于YCOB晶体中三波耦合方程理论模型,在抽运光波形和能量、晶体长度相同的条件下,研究信号光的时间波形对光参变啁啾脉冲放大(OPCPA)光谱和转换效率的影响。计算过程中,抽运光和信号光能量分别为45J和500mJ,光斑直径分别为60mm和50mm。抽运光脉宽取3ns,信号光脉宽为1.2ns。数值结果显示,信号光放大后的光谱和转换效率与输入信号光的时间波形有关。1阶高斯型脉冲光谱的半峰全宽(FWHM)得以展宽,由原来的36nm展宽为放大后的61nm,2阶超高斯脉冲频谱展宽为47nm,高斯脉冲的阶数越高,谱宽展宽越小,5阶和5阶以上的高斯脉冲光谱不再展宽,几乎保持原来36nm不变;1阶高斯脉冲的转换效率最高,达到32%左右,2阶高斯脉冲只有25%,8阶以上转换效率基本变化不大,约为19%。信号光脉冲时间特性对OPCPA的光谱输出和转换效率产生很大的影响。     

LiTaO3光幅度调制器在脉冲调制中的应用

介绍了LiTaO3光幅度调制器，其输出光脉冲峰值功率是-l0dBm，调制电压脉冲宽度为l0ns，重复周期lkHz。直流偏置采用了数字累加平均技术和动态平衡控制技术，在两级串联的情况下，光信号的消光比大于45dB。     

混合型光学双稳态的光脉冲放大

利用一个氦氖-铌酸锂混合型光学双稳态装置实现了固定光偏置和脉冲光偏置两种方式下的光信号放大,光信号增益分别为15和20～95.理论计算和实验结果基本相符.     

Dispersion-compensating Raman/EDFA hybrid amplifier recycling residual Raman pump for efficiency enhancement

We experimentally demonstrate a novel concept of the dispersion-compensating Raman/erbium-doped fiber amplifier hybrid amplifier recycling residual Raman pump for increase of overall power conversion efficiency. The proposed dispersion-compensating hybrid amplifier system has only one pump source for Raman amplification in the dispersion-compensating fiber (DCF) and the residual pump power after the DCF is recycled for secondary signal amplification in an erbium-doped fiber cascaded to the DCF. Using the proposed scheme, we achieve the significant enhancement of both signal gain and effective gain-bandwidth by 15 dB (small signal gain) and 20 nm, respectively, compared to the performance of the Raman-only amplifier.     

全光纤结构高增益脉冲光纤放大器的实验研究

为了探讨多级级联掺镱光纤放大器的脉冲放大特性,采用主振功率放大技术(MOPA),实验研究了3级级联、全光纤结构的高增益脉冲激光放大器。通过优化各放大级增益光纤的长度和抽运光功率的大小,在保证高放大增益的同时,抑制了掺镱光纤中自发辐射光的自生激光振荡,并对第2放大级进行了结构优化。在脉冲激光放大过程中实现了中心波长1064nm、脉冲宽度19ns、重复频率5kHz、峰值功率3.8kW、总放大增益达43.8dB的稳定激光输出。同时,制作完成了1台结构紧凑、全光纤结构的脉冲光纤放大器样机,对重复频率1Hz的低频脉冲信号进行了放大实验,也得到了43.2dB的输出信号增益。结果表明,本脉冲光纤放大器对低频脉冲信号有很好的放大效果。     

新颖的掺铒光纤放大器无源复合组件的研究

报道了一种将光波分复用器与光隔离器集于一体的适用于掺铒光纤放大器的新颖复合组件。根据复合组件的性能指标对组件的结构参数进行了优化设计。实际制作的复合组件，得到泵浦光插入损耗＜０．６ｄＢ，信号光的插入损耗＜１．５ｄＢ，反向隔离度＞４２ｄＢ，体积为９×４５ｍｍ３。将复合组件用于掺铒光纤放大器中（前向泵浦方式）得到约３０ｄＢ的小信号增益，１０ｄＢｍ的饱和输出功率。     

MOPA光纤激光器中放大级自激振荡实验研究

在高功率主振荡功率放大激光器（MOPA）中,放大的自发辐射（ASE）和自激振荡对激光器输出光特性具有显著的影响。基于自行设计并搭建的MOPA光纤激光器系统,研究了自激振荡与泵浦光功率、信号光功率和增益光纤长度之间的关系。结果表明,随着泵浦光强度的增加,自激振荡的功率逐渐增强;在泵浦光功率确定的情况下,增强信号光功率,自激振荡的强度会减小;适当减小增益光纤的长度,对抑制自激振荡也有一定的作用。实验结论对MOPA光纤放大器的研究具有重要的参考意义     

Novel optical hybrid line configuration for quasi-losslesstransmission by distributed Raman amplification

We propose a novel lossless transmission line configuration which exhibits significantly small signal power variation along the line by Raman amplification. A hybrid line consisting of two fibers with different Raman gain properties is theoretically investigated, and it is shown that signal power deviation can be suppressed to only 1.2 dB in a 50-km span. Validity of the proposed hybrid line is confirmed by experiments     

Fabrication and characteristics of GaP-AlGaP tapered waveguide semiconductor Raman amplifiers

We have fabricated GaP-AlGaP tapered waveguide semiconductor Raman amplifiers, and analyzed the effect of tapering in pulse-pumped high-gain operation. The finesse measurement and 80-ps pulse pumped Raman amplification experiment were performed. Although the tapering has caused additional optical loss, the highest gain of 23 dB has been obtained for a tapered waveguide with input facet of 6.0 /spl mu/m/sup 2/ and back facet of 2.9 /spl mu/m/sup 2/ at averaged input power of 170 mW (peak power 26 W). It is shown that the optical loss of the pump light is more severe than the linear optical loss of the signal light when the gain is higher than 20 dB.     

基于小信号放大的掺铒光纤放大器的仿真与实验北大核心CSCD

本文研究并设计了一种掺铒光纤放大器,该EDFA能够有效对微弱光信号功率进行放大。首先在OptiSystem环境下进行理论数值仿真优化,根据仿真优化结果对现有光路进行改进。为对比两种掺杂浓度光纤的增益特性,本文进行低掺光纤和高掺光纤仿真与实验,发现高掺光纤优势较大,选用高掺光纤增益系数可达34.2 dB。相较传统EDFA,选择的高掺光纤长度仅为传统光纤长度的十分之一,并且可以保证增益系数在34 dB以上;其次在缩短光纤长度的条件下对-40 dBm的信号产生较大增益,利用改进的插值法计算测量得到的噪声系数更加精确,较传统放大器低0.3 dB左右,实现较低噪声系数和较高增益。基于以上优点,该放大器已应用于信号光的前置放大系统,对小信号光具有良好的放大效果。     

Design of Hybrid Optical Amplifiers for High Capacity Optical Transmission

This paper describes our design of a hybrid amplifier composed of a distributed Raman amplifier and erbium‐doped fiber amplifiers for C‐ and L‐bands. We characterize the distributed Raman amplifier by numerical simulation based on the experimentally measured Raman gain coefficient of an ordinary single mode fiber transmission line. In single channel amplification, the crosstalk caused by double Rayleigh scattering was independent of signal input power and simply given as a function of the Raman gain. The double Rayleigh scattering induced power penalty was less than 0.1 dB after 1000 km if the on‐off Raman gain was below 21 dB. For multiple channel amplification, using commercially available pump laser diodes and fiber components, we determined and optimized the conditions of three‐wavelength Raman pumping for an amplification bandwidth of 32 nm for C‐band and 34 nm for L‐band. After analyzing the conventional erbium‐doped fiber amplifier analysis in C‐band, we estimated the performance of the hybrid amplifier for long haul optical transmission. Compared with erbium‐doped fiber amplifiers, the optical signal‐to‐noise ratio was calculated to be higher by more than 3 dB in the optical link using the designed hybrid amplifier.     

Power Amplification for FM and PM Signals with Synchronized IMPATT Oscillators

To meet certain requirements for system performance such as broadening the bandwidth, obtaining a high gain for the FM-and PM-signal amplifier, and increasing the power output, the "locking amplifier" composed of cascade-connected and hybrid-combined synchronizing oscillators is described. How the SNR of the amplifier is greatly improved and its gain increased by cascade connection and hybrid combination is discussed. These have been ascertained by experiments. In addition, another broad-band and high-gain synchronizing circuit and its application to pulse code modulation-phase modulation (PCM-PM) signal amplification are also discussed.