基于Mach-Zehnder干涉仪的扫描限幅法用于啁啾脉冲频谱整形  

Scanning amplitude limiting approach for spectral shaping of chirped pulse based on Mach-Zehnder interferometer

作　　者：叶荣[1] 钟哲强[2] 吴显云[1] 谭航[1] YE Rong;ZHONG Zhe-qiang;TAN Hang;WU Xian-yun(College of Physics and Engineering, Chengdu Normal University, Chengdu 611130, China;College of Electronics and Information Engineering,Sichuan University,Chengdu 610064,China)

机构地区：[1]成都师范学院物理与工程技术学院,四川成都611130 [2]四川大学电子信息学院,四川成都610064

出　　处：《光电子．激光》2018年第7期703-707,共5页Journal of Optoelectronics·Laser

基　　金：成都师范学院培育项目(CS17ZD03);成都师范学院人才引进项目(YJRC2015-6);成都师范学院一般项目(CS14ZB03)资助项目;国家自然科学基金(11647094);四川省教育厅重点项目(15ZA0334)

摘　　要：为了补偿啁啾脉冲放大(CPA)中的光谱增益窄化效应,需要对种子激光脉冲进行频谱整形。基于内置KTN电光晶体的Mach-Zehnder干涉仪,提出了一种用于啁啾激光脉冲频谱整形的扫描限幅方法。从理论上分析了KTN电光晶体上加载的静态电压和动态电压对扫描限幅装置透射谱函数的影响,并讨论了电压相对于频率变化的时延和电压自身的抖动对脉冲频谱整形效果的影响。数值结果表明:根据所需要的频谱分布可以逆算得到加载到电光晶体上的电压,从而随时间控制啁啾脉冲各频率成分的透射率,实现啁啾脉冲频谱的整形;采用所提出的扫描限幅方法,对中心波长800nm,啁啾参数等于21 230,对应带宽为20nm的一阶高斯型脉冲进行频谱整形,得到了与所需频谱分布几乎一致的近平顶形状的频谱分布;电压相对于频率变化的时延和电压自身的抖动越大,整形后的脉冲频谱分布与所需频谱相差越远。为了获得与所需频谱一致的整形频谱分布,需要尽量保证电压与频率在时间上的匹配,以及尽量减小电压的抖动。The spectrum of seed pulse is necessary to be shaped to compensate the gain narrowing effect of spectrum in the chirped pulse amplification （CPA）. A scanning amplitude limiting approach for spectral shaping of chirped laser pulse is proposed based on the Mach-Zehnder interferometer （MZI） built in a KTN electro-optic crystal. The effect of the steady-state voltage and the dynamic voltage applied to the KTN electro-optical crystal on the transmission spectra function is researched. And the influence of the time-delay of the voltage variation relative to that of frequency and the own voltage deviation on the spectral shaping is discussed. The simulations shows that the voltage applied to the electro-optical crystal can be inversely calculated according to the needed spectrum shape, and the transmissivity of each frequency component of chirped pulse is controlled with time, which leads to the spectral shaping of chirped pulse. The approximately flat-top spectral shape is obtained which is almost the same as the needed spectrum shape by the proposed scanning amplitude limiting shaping approach, for the first-order Gaussi- an pulse with central wavelength of 800 nm, chirp parameter of 21 230 corresponding to 20 nm band- width. Furthermore,with the increases of the time-delay and voltage deviation,the shaped spectral shape is rarer away from the needed spectrum shape. In order to obtain the identical pulse spectrum as needed, it is necessary to make sure that the voltage matches with the frequency in time and the unfavorable deviations are reduced.

关 键 词：频谱整形 啁啾激光脉冲 扫描限幅 二次电光效应 MACH-ZEHNDER干涉仪 

分 类 号：O433.4[机械工程—光学工程]