增益开关半导体激光器的三级脉冲整形方案

增益开关半导体激光器产生的光脉冲宽度往往较宽,且具有一定大小的脉冲基座。为了提高增益开关半导体激光器的脉冲质量,提出了一种三级脉冲整形方案。首先,利用色散补偿光纤将增益开关半导体激光器输出的光脉冲宽度从39.381 ps压缩到26.681 ps,随后利用掺铒光纤放大器和色散位移光纤的高阶孤子效应进一步将光脉冲的宽度压缩到20.916 ps,最后利用半导体光放大器的自相位调制效应区分开脉冲基座与脉冲中心的光谱,并利用光滤波器滤除脉冲基座对应的光谱部分,从而消减脉冲基座,并将脉冲宽度压缩到18.497 ps。实验结果表明,该三级脉冲整形方案可以有效地压缩脉冲宽度以及减小脉冲基座,从而提高增益开关半导体激光器输出光脉冲的质量。     

大功率半导体激光器的高精度脉冲电源设计

为了满足大功率半导体激光器脉冲应用的实际需求, 针对单脉冲内电流平顶下降问题和重复性情况下电流稳定性降低的问题, 设计了一种多参数宽范围可调的高精度高稳定脉冲驱动电源。该电源以大功率场效应晶体管为核心, 通过现场可编程门阵列产生的高精度时序波形来完成单脉冲内的上升沿调控和栅极控制电压补偿, 通过微控制器结合电流采样的闭环控制方案实现重频运行下的电流高稳定输出。结果表明, 在输出电流100 A、脉冲宽度400 μs、重复频率1 kHz的最大功率输出驱动二极管负载时, 驱动电流上升沿过冲幅度小于0.5%、单脉冲内电流衰减小于0.2%、重复率脉冲不稳定度小于0.1%;在同样输出条件下驱动半导体激光器, 其在单脉冲内光功率过冲小于2%, 重复光脉冲不稳定度小于0.2%。该研究有助于提高脉冲电源脉冲电流稳定性, 对现有脉冲电源结构的改进具有一定的参考意义。     

瓦级半导体激光器光束整形装置

介绍了一种采用光束远场发散角分割的方法 ,利用已有专利的微片棱镜堆光束整形器 ,对瓦级半导体激光器光束整形 ,该装置由半导体激光器、微柱透镜、柱面透镜、微片棱镜堆、聚焦系统和光纤组成 ,该方法可在一定程度上改善整形效果 ,具有结构简单、加工和装配容易的优点     

半导体激光器超短光脉冲测试技术

用ＰＯＭ有机晶体作倍频器件，建立了超短光脉冲强度自相关检测系统，并用于半导体超短光脉冲的脉宽测量，灵敏度比以ＬｉＩＯ３为培频晶体的系统提高６ｄＢ．     

半导体激光器皮秒光脉冲产生技术

本文概述半导体激光器皮秒(ps)光脉冲产生的方法,这些方法包括锁模、增益开关、电反馈、光电反馈和Q开关等,并报道了各种方法产生ps光脉冲的现有水平及未来展望。     

增益开关半导体激光器产生高重复率的ps光脉冲

本文报道用增益开关1.3μm InGaAsP半导体激光器产生 ps光脉冲,光脉冲宽度(FW·HM)随频率在 16—23 ps之间变化,重复频率在 1—5 GHz范围连续可调.     

高功率半导体激光器微光学光束整形技术

基于微光学光束变换系统方法,采用双微棱镜列阵、同轴“之“字形整形方法、反射棱镜阵列法等技术对准直光束进行折叠及光参数积匹配变换,实现光束的完全消像散;利用自行研制的大数值孔径连续非球面微透镜列阵、整形器件等核心微光学器件,实现了准直、聚焦和光纤输出等各种功能。形成了系统的半导体激光器光束整形变换技术,准直后光束发散角达到理论极限;成功获得高效率单芯径光纤耦合半导体激光器泵浦源。     

用于激光脉冲整形的电脉冲产生技术

介绍了一种用于激光脉冲整形的超宽带脉冲产生方法.电路中利用阶跃恢复二极管(SRD)载流子可控、截止速度快的特点,采用对阶跃恢复二极管进行串并联相结合的方法设计了超宽带脉冲产生电路.给出了实际电路的测试结果,并且对实验结果在物理层面上进行了理论分析,实验结果与理论分析结果吻合.此脉冲产生电路可输出幅度约10V,脉冲宽度约...     

A scheme of picosecond pulse shaping using gain saturationcharacteristics of semiconductor laser amplifiers

To obtain high power, well shaped picosecond pulses from gain-switched semiconductor lasers, the use of dynamic gain saturation characteristics of semiconductor laser amplifiers was investigated theoretically and experimentally. A configuration of a reflected-wave amplifier (RWA) with single-side external coupling is introduced for pulse shaping, which is found to be suitable for enhancing dynamic gain saturation. By a combination of a distributed feedback laser oscillator at 1.3 μm in wavelength and a reflected-wave amplifier of 400 μm cavity length with asymmetric facet reflectivities of 0.01% and 30%, single-mode optical pulses with almost no tailing, full width at half maximum of 15 ps, and peak power exceeding 50 mW were obtained without pulse broadening, despite the considerable tail structure of the incident pulse     

Optical processing based on spectral line-by-line pulse shaping on a phase-modulated CW laser

We demonstrate optical processing based on spectral line-by-line pulse shaping of a frequency comb generated by phase modulating a CW laser and show various applications including CW-to-pulse conversion, width/wavelength tunable return-to-zero pulse generation, pulse-to-CW conversion, wavelength conversion, and microwave photonics. The correlations between optical spectra, time-domain waveforms, and RF spectra are quantitatively studied.     

PAPR reduction based on improved Nyquist pulse shaping technology in OFDM-RoF systems

High peak-to-average power ratio (PAPR) is the main disadvantage in orthogonal frequency-division multiplexing (OFDM) communication systems, which also exists in OFDM-radio over fiber (RoF) systems. In this paper, we firstly analyze the impact of high PAPR on a 40 GHz OFDM-RoF system, and then describe the theory of Nyquist pulse shaping technology for reducing PAPR. To suppress PAPR further, an improved Nyquist pulse shaping technology is proposed, in which the distribution of original-data amplitude is changed by properly selecting the time-limited waveforms of the different subcarriers. We firstly apply the improved Nyquist pulse shaping technology to an OFDM-RoF system. The simulation results show that PAPR is effectively reduced by more than 2 dB with the bit error rate (BER) declining by about 0.125%.     

Optical pulse shaping by cross-phase modulation in a harmonic mode-locked semiconductor fiber ring laser under large cavity detuning

The authors experimentally investigate the phenomena of the pulse-shape distortion due to the drift of cavity length or modulation frequency in a harmonically mode-locked semiconductor fiber ring laser (SFRL). Also, it is experimentally demonstrated that the optical pulse shaping by cross-phase modulation (XPM) can be applied to enhance the robustness of a harmonic mode-locked semiconductor ring laser to the environmental factors, e.g., the modulation-frequency drift and/or the cavity-length drift. The mechanism of pulse-shape distortion due to the modulation-frequency drift or cavity-length drift is explained and experimentally verified. As the locking condition of the SFRL goes to the rational harmonic mode-locking (RHML) regime, the pulse-shape distortion becomes dominant. To validate the explanation, a simple equation for estimating and comparing the amount of cavity-length detuning in terms of frequency is proposed for comparison, which is called the equivalent frequency detuning (EFD). The distortion mostly appeared in the trailing edge of the pulse. By selectively filtering the XPM-induced red-chirped wavelength components in the rising edge of the pulse, the mode-locked pulse train with large pulse-shape distortion can be reshaped to regenerate a mode-locked pulse train with less pulse-shape distortion than the pulse train without the proposed scheme. This method can be used to reduce the pulse-shape distortion effectively, maintaining the pulse repetition rate under the large modulation-frequency detuning, or equivalently, large cavity-length detuning. The proposed scheme is able to generate the pulse-trains robust to the modulation-frequency drift and/or cavity-length drift of the mode-locked SFRL.     

基于嵌入式技术的可控光纤激光脉冲光源

为了得到一种功率可控的光纤激光脉冲光源,采用窄脉宽低重频脉冲光作为种子源,以掺镱光纤为增益介质,利用嵌入式控制技术和脉冲抽运技术,实现了全光纤脉冲激光的多级放大和信噪比提升。结果表明,此种光源输出稳定、信噪比良好,不仅降低了热效应危害,还增强了抽运能量的提取效率,可以作为一般大功率光学系统的光源使用,具有良好的应用价值,市场前景广阔。     

激光二极管光束整形技术

阐述了对LD输出光束进行整形的必要性。在国内首次对目前常用的一些典型的光束整形技术的整形原理、关键技术及整形效果进行了分析、比较和评价。     

脉冲式半导体激光器准直光学系统的设计

根据具体的探测环境和探测精度,通过理论分析,提出了脉冲式半导体激光器准直光束的单透镜设计方法和柱面透镜的设计方法,并且给出了具体的设计参数。可以获得高斯光束的准直发散角为1.48mrad;高斯光束的腰粗为0.325mm。     

基于传输线的纳秒脉冲成形电路研究

提出了一种脉冲成形和脉冲展宽的方法,在基于理想开关的纳秒脉冲成形电路基础上,使用MOS管代替理想开关,保证MOS管工作在饱和区实现了脉冲成形,分析了MOS开关进入饱和区后在不改变传输线延迟时间的情况下,改变电源电压可以实现脉冲展宽,并通过实验验证了仿真获得的结果。