基于数字脉冲整形技术的可变光谱宽度相位调制研究  

Phase Modulation Research on Variable Spectral Width Based on Digital Pulse Shaping Technology

作　　者：龚雨枫 汪小超[1] 唐阳慧 徐首英 周申蕾[1] Gong Yufeng;Wang Xiaochao;Tang Yanghui;Xu Shouying;Zhou Shenlei(National Laboratory on High Poiver Laser and Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海光学精密机械研究所高功率激光物理联合实验室,上海201800 [2]中国科学院大学,北京100049

出　　处：《中国激光》2021年第20期78-84,共7页Chinese Journal of Lasers

基　　金：中科院先导项目(XDA25020304)。

摘　　要：高功率激光驱动器中多采用谱色散匀滑(SSD)的束匀滑技术,而SSD中的相位调制常使用等幅相位调制。为进一步改善匀滑效果,提高动态调控能力,提出一种特异性相位调制技术,即采用调制深度为时变函数的特异性调制方式来获得光谱宽度可随时间变化的信号输出。基于相位调制的频谱理论,分析了特异性相位调制后的激光频谱特性。利用任意波形发生器(AWG)整形输出的特定相位调制信号开展实验研究,通过改变AWG输出两路电信号的相对时间差,得到250 ps的信号光在3 ns内不同时间点的调制光谱,实验结果与理论模拟结果一致。这种调制方式可以完成光谱宽度的连续实时调控,这对于高功率激光驱动器的激光参数控制中实现动态的光谱色散匀滑有着重要应用。Objective In the implosion process of laser inertial confinement fusion(ICF),several requirements are proposed for the uniformity of the target irradiation and various beam-smoothing techniques,including spectral dispersion smoothing(SSD),have been developed and applied.According to different physical processes,different physical parameters are adopted in different periods to further improve the focal spot smoothing effect.Considering OMEGA as an example,the main pulse generated by its front end is divided into two parts,corresponding to SSD.In the initial part of the pulse,high-frequency multifrequency phase modulation is used to achieve a wide bandwidth output to obtain a better smoothing effect.The relatively narrow spectral width output can smooth the main pulse and suppress the stimulated Brillouin scattering.Finally,the initial part of the pulse and the main pulse form a complete pulse output through the beam combination.The modulation requirements of the pulse light in the main pulse front end of the OMEGA device differ at different time points.However,the pulse light in the main pulse front end of the OMEGA device is realized by splicing time and space;the optical system is relatively complex.Therefore,it is necessary to implement a scheme that can achieve different modulations at different time points,changing the corresponding spectral width.The scheme can meet different spectral width requirements of different time points in the pulse light without beam-splitting modulation.Methods This study investigates the specific phase modulation technology.The specific phase modulation function is obtained by integrating original phase change function of the target.It is essential that the modulation depth of the specific phase modulation function is a time-varying function.The spectrum width can be changed at any time using a specific phase modulation function to modulate the phase of the pulse light.Based on phase modulation spectrum theory,the spectrum characteristics of the laser with a specific phase modulat

关 键 词：激光光学 相位调制 光谱宽度 光谱色散匀滑 惯性约束核聚变 

分 类 号：O436[机械工程—光学工程]