基于注入锁定的涡旋脉冲激光功率放大技术研究

涡旋激光由于其具有螺旋相位结构和不同轨道角动量态彼此正交的特性，使其在自由空间光通信领域有着无可替代的应用前景。但受制于可编程相位调制器的损伤阈值，难以获得兼有阶次可调和高峰值功率的涡旋脉冲激光，使其在自由空间光通信应用时无法实现远距离传输。针对这一问题，本项目开展基于注入锁定的涡旋脉冲激光功率放大技术研究，通过建立基于单晶光纤的涡旋激光功率放大理论模型，揭示涡旋激光在单晶光纤放大器中相位分布、模式纯度及放大效率的调控规律；掌握注入锁定激光器中涡旋种子对脉冲激光的横模牵引机制，突破可编程相位调制器损伤阈值的限制，研制出阶次可调的高峰值功率涡旋脉冲激光器，阶次可调范围为-10至+10阶，单脉冲能量大于4毫焦；并研究利用遗传算法预矫正涡旋种子激光技术，实现涡旋脉冲激光的模式纯度提升及混合模式的产生。通过本项目的研究，能够为涡旋脉冲激光在远距离自由空间光通信的应用提供充分的科学依据和技术储备。

Due to the special structural phase and the orthogonal orbital angular momentum (OAM) states, vortex beam has important applications in fields of free-space optical communication. However, limited by the damage threshold of the programmable spatial light modulator (SLM), it is very hard to achieve high energy vortex pulses with a controllable OAM state which are necessary for remote free-space optical communication. In view of the above problem, this project plans to study on power amplifier of vortex pulsed laser using injection-locking technology. By building the theoretical model based on vortex laser power amplifier with single-crystal fiber (SCF)，parameters which influence the phase distribution, the purity of vortex laser mode and the gain of the amplifier are studied; The influence of the vortex seeder on the transverse mode of the slave laser is theoretically and experimentally explored. The limitation of the damage threshold of the SLM is breakthrough, thus the vortex pulsed laser with high peak power and tunable OAM state is developed. The OAM states can be changed from -10 to +10, and the energy of the single vortex laser pulse is larger than 4 mill joule. Then, the genetic algorithm (GA) is used to improve the purity of vortex pulsed laser and generate the mixed-mode vortex pulsed laser. Through the research of this project, we hope to provide necessary technical reserves for the remote free-space optical communication using vortex pulsed lasers.