面向超短脉冲相干组束的时间同步测量与控制研究

Coherent beam combining (CBC) of ultrashort ultrahigh intensity laser systems is one of the main solutions to acquire ultrahigh focal intensity(10^23～10^25 W/cm^2). It is of significant scientific importance for researches such as high-energy-density physics, strong field physics, astrophysics and so on. According to the urgent requirement of pulse timing in CBC, a method of timing measurement and control with wide detection range and high precision is proposed, the core of which is based on balanced optical cross correlation (BOC) and electrical energy interferometry (EEI). The basic principle and physical model of BOC and EEI are analyzed theoretically, which will be the guidance for experimental design. In experiment, the methods of BOC and EEI are used to measure and control the timing of ultrashort pulses, respectively. On the basis, the two methods are combined effectively for realization of timing measurement and control with wide range and high precision. This study will provide a good solution of timing for CBC in ultrashort ultrahigh intensity laser systems.

超短超强脉冲激光系统的相干组束是获得超高聚焦峰值功率密度(10^23～10^25 W/cm^2)的主要途径之一，对高能密度物理、强场物理、天体物理等领域的发展具有十分重要的科学意义。本项目针对超短超强脉冲激光相干组束急需的时间同步技术，开展超短脉冲大范围、高精度时间同步的测量与控制研究，其核心是将平衡式光学互相关法与电学能量干涉法相结合。理论上，将重点研究平衡式光学互相关法和电学能量干涉法的基本原理，建立相应的物理模型，指导实验的优化设计。实验上，分别开展平衡式光学互相关法和电学能量干涉法测量与控制超短脉冲时间同步的研究，并以此为基础将两种方法有机结合，实现大范围、高精度的超短脉冲激光时间同步测量与控制。本项目有望为超短超强激光系统的相干组束提供时间同步解决方案。

针对超短脉冲激光相干组束急需的时间同步技术，开展超短脉冲大范围、高精度时间同步的测量与控制研究。该方法基于脉冲间相对延时引起的组束脉冲时域调制特性。开展了平衡式光学互相关法和电学能量干涉法测量时间同步的理论分析。采用脉宽为237fs的超短脉冲搭建了演示实验平台，将光学互相关法与电学能量干涉法相结合，利用两步法实现两束脉冲的大范围、高精度时间同步测量与控制。实验结果表明，1小时内两脉冲的时间同步抖动PV优于700as，平均相干组束效率可达91.6%。本项目的研究有望为未来大口径超短超强激光系统相干组束所需的时间同步技术提供解决方案。