Multilayer dielectric thin film reflector for spectrum reshaping of chirped pulse laser in Nd : glass chirped pulse amplification system

在千焦拍瓦高功率啁啾脉冲放大系统设计中,为了尽量消除增益窄化和增益饱和效应的影响,同时尽可能提高高功率激光输出脉冲信噪比参数,激光脉冲时空和光谱的整形问题备受关注.提出一种光谱整形新方法,利用特定结构的多层介质膜反射镜,可实现对大能量高功率啁啾脉冲钕玻璃放大系统中啁啾脉冲的光谱整形.研究结果表明,只要合理选择多层介质膜系的结构参数,可有效地控制其反射率分布,且在保证反射相位基本不变的条件下其调制度可超过60%.针对钕玻璃1053nm波长设计而成的光谱整形反射镜,反射带宽可达到196nm,色分辨率约为0.1nm,在几十纳米波长范围所对应的相位偏差小于12mrad,相当于λ/524,能够满足"神光Ⅱ"千焦拍瓦改造的技术指标要求.In order to compensate for the gain narrowing and gain saturation effects, and also to improve the signal to noise ratio of the output high-power laser pulse, lots of attention have been paid to the spatial distribution, the temporal profile, as well as the spectrum reshaping in the design of kilo-joule peta-watt chirped pulse amplification (CPA) systems. In this paper, a new method for the spectrum reshaping is proposed, which utilizes a multilayer dielectric thin film reflector with specific construction to realize the spectrum reshaping of the chirped pulse laser in large energy and high power Nd: glass CPA system. The results show that the reflectivity distribution of the multilayer dielectric film reflector can be controlled effectively only if the parameters of the thin film reflector are chosen appropriately. The spectrum modulation radio can be varied over 60% under the condition that the phase of the reflecting light remains nearly constant. The thin film reflector designed for spectrum reshaping of the Nd:glass CPA system with the central wavelength of 1053 nm exhibits a bandwidth of reflect light of 196 run, the chromatic resolving capability of about 0. 1 nm and the phase aberration in the range of the tens of nanometer of up to 12 mrad, which can meet the requirement of the "Senguang-H " kilo-joule peta-watt reconstruction project.Outstanding Young Researchers Foundation of Sichuan Province, China [05ZQ026-013]; University of Ministry of Eduction, China [NCET-05-0784