基于多光子吸收的超快激光系统光稳幅技术研究

High-energy ultrafast pulsed laser has important applications in strong field physics researches such as X ray laser, inertial confinement fusion, laser particle accelerator, etc. The output pulse energy stability is a very important index, deciding the success rate and reliability of experimental results. The pulse energy fluctuation of a high-energy laser setup can be high up to 20%-30% due to the serious thermal effect, stress and optical inhomogeneity induced by size amplification effect, which is very disadvantage to strong field physics experiments. The pulse amplitude stabilizer adopted at present based on the principle of electro-optic switch has a big shortcoming of high inherent loss. Usually the output energy is only equal to 50%-60% of the input. The late-model optical stabilization device based on the multi-photon absorption principle has advantages of small inherent loss, simple structure, and easy to use, which is the most ideal method for improving the pulse output stability. In this project we plan to design and synthesis new multi-photon absorption materials for 800nm broadband pulsed laser, to fabricate module type optical stabilizer with over 90% transparency, and to explore its feasibility in high-energy ultrafast laser systems, which may explore an economic and effective method to improve the domestic high-energy laser output stability and further to improve the domestic strong field physics research levels.

超快超强脉冲激光在X射线激光、惯性约束聚变、激光粒子加速器等强场物理研究领域有着重要的应用。激光器输出脉冲能量的稳定性是一个非常重要的指标，决定着实验结果的成功率与可靠性。由于大尺寸导致的热效应、应力与光学不均匀性比较严重，往往使得大能量脉冲激光系统相邻脉冲间的能量起伏较大，有时能高达20%-30%，非常不利于强场物理实验的开展。目前普遍采用的基于电光开关原理的脉冲稳幅器存在固有损耗大的缺点，通常输出能量只有输入能量的50%-60%。基于多光子吸收原理的稳幅器件具有固有损耗小、结构简单、使用方便的优点，是改善脉冲激光输出稳定性的最理想方法。本项目计划针对800nm宽带脉冲激光设计、合成基于多光子吸收的新型光稳幅材料，研制透过率大于90％的模块型光稳幅器件，探索其在大能量脉冲激光系统上使用的可行性，为提高国内大激光装置的输出稳定性、进而不断提高强场物理研究的水平探索经济有效的新方案。

超快超强脉冲激光在强场物理研究领域有着重要的应用。由于大尺寸导致的热效应、应力与光学不均匀性比较严重，通常大能量脉冲激光系统相邻脉冲间的能量起伏较大，非常不利于强场物理实验的开展。基于多光子吸收原理的稳幅器件具有固有损耗小、结构简单、使用方便的优点，是改善脉冲激光输出稳定性的最理想方法。本项目针对800 nm宽带脉冲激光器，设计、合成了15种基于双光子吸收的新型光限幅化合物，通过基础性质研究，优选出综合性能较好的3种化合物，结合固体支持介质的筛选，最终制备出既具有优良光热稳定性又具有明显光限幅效果的固体器件。器件光程为10 mm，在800 nm±30 nm波长范围透过率大于90％，对800 nm的飞秒和皮秒超快激光器均具有光限幅的作用，能使激光输出稳定性提高~35%，达到了项目的预期目标。上述研究成果已发表学术论文3篇(其中SCI收录2篇)，申请中国发明专利1项。