高功率飞秒激光脉冲相干组束技术研究

The ultr-intense and ultra-short lasers with focused intensity of 1023W/2 and higher will open series of new research frontier areas in high intensity physics. Therefore, the lasers with peak power of 10 PW to 100 PW and even higher are needed. According to the very recent development, the technologies of laser amplification and compression based on the large aperture gain medium and large size compressor cannot afford it at the moment. It is necessary to develop a new and effective method to solve this problem. The technology of coherent beam combing (CBC) is an effective and alternative method, which is studied and demonstrated in fiber lasers, CW and long pulse lasers. However, the research of CBC on high power femtosecond (fs) lasers is in the startup stage, and there are many obstacles need to be removed. In this project, we proposed that the main factors which affect the efficiency of CBC have to be researched by theoretical modulation and experiments. The laser beam properties amplified by chirped pulse amplification (CPA) and optical parametric chirped pulse amplification (OPCPA) need to be measured and analyzed. Importantly, we will develop the technology of balanced optical cross-correlation (BOC) combined with active feedback loop, to achieve CBC of high power fs laser pulses at different repetition rate with different power. Finally, we will achieve CBC of fs pulses with peak power of TW even PW level with efficiency of 90%. Through this project, we will develop a feasible technology for the future development of ultra-intense and ultra-short lasers.

聚焦密度超过1023W/cm2的超相对论超强超短激光，将开拓一系列强场超快科学的新前沿新方向，需要峰值功率超过10PW达到100PW乃至更高量级的激光脉冲。因此，依赖大口径增益介质的放大和压缩技术遇到严峻挑战，急需发展新型技术解决这一科学难题。激光相干组束技术是提升焦场聚焦功率密度的一个有效途径，高功率飞秒激光脉冲的相干组束技术刚刚起步，面临一系列的关键技术需要突破。本项目提出通过分析影响飞秒激光脉冲相干组束的关键因素，研究多路啁啾脉冲经过不同CPA或OPCPA放大和压缩器器后的光束主要性能演变，发展基于脉冲正入射式平衡交叉相关（BOC）技术路线的多路飞秒激光脉冲高精度同步测量技术，结合高精度实时伺服反馈控制系统，解决不同量级、不同重复频率下高功率飞秒激光脉冲相干组束的关键技术，实现太瓦甚至拍瓦级飞秒激光脉冲相干组束，组束效率达到90%，为超强超短激光长远性能提升探索发展一条可行的技术路线

本项目按照预期目标和时间节点，从理论分析、实验平台建立、关键技术发展和实验验证等多个方面开展相关研究，取得多项创新性成果，完成了研究计划，达到项目预期目标。通过建立理论模型，对飞秒激光脉冲相干组束关键问题进行了理论研究，定量分析了子光束间各个参数对组束效率的影响，为实验研究提供了理论指导，并且进一步提出了一种基于深度学习算法的相位误差和指向性误差参数控制算法，模拟分析了其可行性；针对飞秒脉冲相干组束的独特性能，创新发展了三种高进度脉冲同步控制技术，为多光束相干组束提供了技术支撑；建立了kHz飞秒CPA激光脉冲相干组束实验平台，为开展多路飞秒激光脉冲相干组束实验研究创造条件；基于压电陶瓷主动控制器件（PZT）和相位测量与控制方法，建立了一套主动控制闭环回路系统，用于实现双光束组束系统中相位误差的测量与控制，实现了两路千赫兹飞秒脉冲激光的相位锁定，相位锁定精度高达λ/51，并在焦平面上实现了高达93%的相干组束效率；针对高能量、底重复频率飞秒激光脉冲对组束技术的需求，开展了基于CPA放大器的百 mJ 量级、重复频率为1HZ的双路飞秒激光脉冲相干组束实验研究，验证了CPA放大器用于高功率飞秒激光相干组束的可行性，发展了适用于低重复频率（1HZ）双脉冲同步控制精度达到百阿妙量级的同步精度测量和伺服反馈控制系统，首次在实验上实现了实现百 mJ 量级下组束效率超过 90%的两路飞秒激光脉冲的相干组束；开展了四路飞秒脉冲相干组束实验研究，实现了四光束间的相位误差锁定，实验验证了四路飞秒激光脉冲相干组束的可行性，为相干组束技术在高功率超快激光输出强度进一步提供了创新性技术途径。项目执行期间以第一标注在 SCI 核心期刊发表学术论文 11 篇，申请发明专利 3项,软件著作1项。在国际、国内学术会议邀请报告两项。