脉冲LD间歇抽运2微米注入锁频激光器的研究

The 2μm injected-locked laser diode-pumped solid-state laser has become the focus of research in the field of laser radar, optoelectronic countermeasures, laser medical and diagnostic. This project highlights two problems. The one is to solve the low frequency operation of 2μm Q-switched laser. The concept of pulse-LD-intermittent-pumped technology has been proposed innovatively. The thermal field distribution within the laser medium and the optical field distribution within the cavity will be analyzed theoretically after. A new resonant cavity will be designed to achieve high-repetition-rate and large-energy 2μm Q-switched laser.The other is to solve the loss-locking of the injection-locked laser. The internal-optical-field distribution model with temperature parameters of injection-locked laser will be built first time. The light field distribution in the entire resonator will be analyzed and solved in detail when the internal temperature of the laser medium changed or the Q-switch in the state of open and close. Then the necessary optical and electrical compensation methods will be adopted to improve the mode-matching between the master laser and slave laser. Then the high repetition rate and large energy injection-lockes laser will be achieved. The project will make technological breakthroughs of 2μm injected-locked laser. And it will provide the academic foundation and technical means in the injection-locked lasers to wider application and development.

激光二极管泵浦的2μm注入锁频固体激光器已成为激光雷达、光电对抗、激光医疗和诊断等领域的研究重点。本次项目申请的主要研究内容包括两个方面，一是为解决2μm调Q激光器运转频率低的问题，创新性地提出脉冲LD间歇抽运技术的概念，理论分析脉冲LD间歇抽运下激光介质内部的热场分布，设计适用于该新技术的自热补偿谐振腔型，实现2μm调Q激光器的高重频、大能量激光输出。二是为解决注入锁频激光器的失锁问题，首次建立含有温度参量的单掺铥调Q激光器内部光场分布模型，分析和求解激光介质内部温度变化以及Q开关处在开启和关闭状态对整个谐振腔内光场分布的影响，根据求解结果设计种子光注入光学系统，以提高种子激光与从激光器振荡光路的匹配度，实验上获得有效的锁频信号，进而实现高重频大能量的单掺铥激光器锁频激光输出。通过本项目的研究有望实现2μm注入锁频技术的新突破，为注入锁频激光器的更广泛应用和发展提供理论基础和技术手段。

2µm固体激光器具有人眼安全、大气消光比低、体积小等优点，使其成为相干多普勒测风激光雷达和差分吸收激光雷达的首选光源。注入锁频技术在固体激光器中的应用，使输出激光脉冲同时具备单纵模、窄线宽、高频率稳定度、足够单脉冲能量和脉冲宽度的特点，满足相干多普勒测风激光雷达对激光光源的要求。. 本项目提出采用脉冲LD间歇抽运技术，缓解激光工作物质的热效应，提高激光器的运转频率，最终将该技术应用到2μm注入锁频激光器中。主要研究内容包括：.基于解决准三能级激光运转受较为严重的热效应影响，对脉冲 LD间歇抽运技术进行理论分析和计算，克服单掺铥激光介质自身能级寿命长，不适于实现高重频调 Q 激光输出的缺点，获得实现高重复频率和大能量 2μm 锁频激光器的技术途径。. 理论仿真脉冲 LD 间歇抽运激光介质时晶体内部的热场分布情况，证明脉冲LD间歇抽运技术对于缓解工作物质热透镜效应、提高运转频率和输出能量的可行性。设计适于脉冲 LD 间歇抽运的热自补偿谐振腔，进而获得高重频单掺铥调 Q激光输出。. 基于模式匹配理论，设计和搭建了种子光注入光路，并对注入后种子激光的传输与变换进行了理论分析和模拟，提高了种子激光与从激光器振荡光路的匹配度，实验上获得了有效的锁频信号，为单掺铥激光器锁频脉冲激光输出奠定了基础。. 最终，实现了脉冲LD间歇抽运Tm:YAG 2μm固体激光输出，重频1kHz下，最大单脉冲能量为4.42mJ，脉冲宽度为406.1ns；实现了脉冲LD间歇抽运Tm:YAG 2μm锁频固体激光输出，重频500Hz下，最大单脉冲能量为3.83mJ，脉冲宽度为398.7ns。实验结果表明，采用脉冲LD间歇抽运技术可以有效缓解工作物质的热效应，提高激光器的运转频率和输出单脉冲能量。该技术可以被应用于其他发射截面小、热效应严重的激光工作物质上，进而提高激光器运转重复频率和输出能量，具有重要的科学意义和一定的应用前景。