基于增益光栅的调Q脉冲单频固体激光器稳频机理研究

With the self-adaptive ring resonator based on the gain grating, the frequency stabilization mechanism of an injection-seeding Q-switched pulsed single frequency laser is investigated, aiming at improving frequency stability, reliability and anti-jamming capability of single frequency output laser. Dynamic characteristic in two spatial dimensions of the gain grating is studied to get access to ways of increasing the lateral light field variation range in the gain grating. Moreover, inserting relative elements in the cavity to control the inner cavity beam size is investigated. This method suppresses inconsistent of phase conjugate reflectivity, eliminates the effects of beam transverse shape and beam position change of the interacting beams on dynamic range, and reveals frequency stabilization mechanism in the gain grating acting region of the injection-seeding ring resonator, therefore improving frequency stability, reliability and anti-jamming capability of the single longitudinal mode output laser. By optimizing the parameters of the optical elements in resonator, Q-switched pulsed single frequency laser with high frequency stabilization, high repetition rate, high pulse energy, good beam quality will be obtained. Besides, researching on the anti-jamming capability of the frequency stabilization system and acquiring the critical technologies with independent intellectual property rights, this project will provide a novel way to improve reliability of such laser system, simultaneously offers great support to research on the lidar, optoelectronic countermeasure system and other systems.

采用基于增益光栅的自适应环形激光谐振腔结构，开展种子注入调Q脉冲单频激光器稳频机理研究，提高单频输出激光的频率稳定性、可靠性和抗干扰能力。研究增益光栅的二维动态特性，获得增加增益光栅的横向光场变化范围的途径；研究在腔内插入相关元件变换腔内光束尺寸方法，抑制相位共轭反射率不一致，消除相互作用光束的横向形状和光束位置变化对稳频的影响，揭示种子注入环形激光谐振腔扩展增益光栅作用区域稳频的机理；优化谐振腔光学元件的参数，获得高重复频率、大脉冲能量、高光束质量的调Q脉冲单频稳频激光输出；研究稳频系统的抗干扰特性，获得具有自主知识产权的关键技术，为探索调Q脉冲单频稳频激光器可靠性的提高提供一新途径，为激光雷达、光电对抗等系统的研究提供支撑。

理论上分析了介质中主要存在的增益光栅，包括透射光栅和反射光栅，对饱和增益介质中的简并四波混频横向二维特性进行分析。分别讨论了稳态，瞬态和一般时间状态下四波混频的相互作用特性。.针对非互易式单频脉冲激光器进行了结构设计，确定了激光器结构，增益介质，泵浦源的参数，分析了输出，泵浦，介质增益三者的关系。为保证环路的增益，采用Nd:YVO4作为增益介质。设计了掠入射式结构，使系统紧凑的同时保证自交叉光夹角足够小，提高增益光栅的衍射效率和输出效率。.采用非互易式环形脉冲激光器结构进行实验，获得了自启动的单频脉冲输出。为提高输出脉冲能量和单频稳定性，通过优化输出镜、非互易式原件分辨偏振光的能力、自交叉光的交叉角以及增益光栅区域与泵浦区域的匹配的方法，从整体上提高了整个增益光栅激光系统的匹配程度，得到单脉冲能量0.9mJ，脉冲宽度8ns，重频10Hz，线宽约0.98pm的稳定单频输出。.在自启动单频脉冲输出的基础上，采用外部种子沿着信号光方向注入环路，引导增益光栅形成，使增益光栅记录种子光的全部信息。首次得到了中心波长在种子光的谱线范围内的稳定输出，证明了通过增益光栅实现稳频输出的构想。