基于Tm,Ho共掺固体激光器的可控光学双稳态及光开关研究

The output wavelength of Tm,Ho codoped solid state lasers is 2μm, which is in the eye-safe waveband and has good atmosphere penetrability. Thus Tm,Ho codoped solid state lasers have important applications in the fields of laser communications, remote sensing, and photoelectric countermeasure. To solve the critical technical issues of optical switch in 2μm laser communications, the project aims to deeply investigate the physical mechanism of optical bistability in Tm,Ho codoped solid state lasers, to explore a convenient method of tuning the bistability region width, and to realize the 2μm waveband controllable optical switch based on optical bistability. The main research contents as following: (1) The quasi-three -level rate equation theory model of optical bistability is established in Tm,Ho codoped solid state lasers. The steady-state and dynamic output performances of the optical bistability lasers are systematically investigated，and the basic physical mechanism and necessary condition of optical bistability are revealed. (2) The influences of changeable parameters on the bistability region width of bistable laser are investigated, and the stable tuning of the bistability region width is realized in a certain range. (3) On the basis of theoretical analysis of bistability switch kinetics, the design scheme of optical switch is optimized, and the 2μm waveband bistable switch controlled by the pump beam is realized for the first time in a Tm,Ho codoped optical bistability solid state laser. The reseach results of the project can be applied to the systems such as 2μm laser atmosphere communications, optical memory, optical storage, and so on.

Tm,Ho共掺固体激光器的输出波长为2μm，处于人眼安全波段，大气穿透性好，在激光通信、激光遥感和红外光电对抗等领域有着重要的应用价值。为解决2μm激光大气通信的可控光开关这一关键基础技术问题，本项目拟深入研究Tm,Ho共掺固体激光器产生光学双稳态的物理机制，探索调节双稳区宽度的有效方法，实现基于光学双稳原理的2μm波段可控光开关器件。具体开展以下研究内容：(1)建立光学双稳Tm,Ho共掺固体激光器的准三能级速率方程理论模型，研究双稳激光器的稳态和动态输出特性，揭示其光学双稳态产生的物理机理和必要条件；(2)研究各可变参数对双稳激光器双稳区宽度的影响，以实现双稳区宽度在一定范围内的稳定可调；(3)在对双稳开关动力学理论分析的基础上，优化设计方案，首次在光学双稳Tm,Ho固体激光器中实现由抽运光控制的2μm波段可控双稳光开关。本项目的研究结果可应用于2μm激光大气通信、光记忆和光存储等系统。

激光二极管泵浦Tm-Ho共掺固体激光器的输出波长为2μm，具有人眼安全、大气穿透性好等优点，在激光大气通信、激光测距、遥感、光电对抗等领域有很好的应用前景。同时，它还是获得3~5 μm、8~12 μm波段光学参量振荡器的理想抽运源。目前，美国、日本等有实力的国家都纷纷开展了2μm固体激光器相关的科学探索与应用研究。光学双稳器件由于其在高速激光通信、光学图像处理、光存储、以及光学逻辑元件等方面的潜在应用价值引起了人们极大的关注。本项目围绕2μm Tm-Ho共掺激光器的光学双稳态、光学双稳光开关等关键问题展开研究，主要的内容如下：.(1) 在详细分析Tm,Ho激光系统粒子跃迁过程和泵浦光传输特性的基础上，建立Tm,Ho激光器的光学双稳稳态速率方程理论模型，研究激光器的稳态双稳输出特性，探讨能量传递上转换以及Tm,Ho激光器重要参数（如出镜透过率、谐振腔长、Ho3+离子掺杂浓度、晶体温度以及谐振腔损耗）对跳变阈值、跳变功率和双稳区宽度的影响，阐明Tm,Ho激光器光学双稳态的物理机制，给出调节双稳区宽度的有效方法。(2) 建立了Tm,Ho激光器的动态光学双稳速率方程理论模型，研究了激光器的动态双稳输出特性，分析泵浦光正负脉冲的幅度和宽度、以及预泵浦持续时间对双稳激光器开关时间以及延迟时间的影响，给出实现双稳光开关的条件。(3) 对Tm,Ho:LLF激光器的光学双稳输出特性开展详细的实验研究，实现了由抽运光控制的2μm波段可控双稳光开关。首先，获得不同腔长条件下多模光学双稳激光输出，分析多模输出的2μm激光偏振特性。然后，通过腔内插入固体标准具，实现Tm,Ho:LLF激光器单纵模光学双稳激光输出，并通过控制标准具的倾角，实现2μm激光的偏振及波长的切换。最后，实现基于Tm,Ho:LLF激光器光学双稳态的可控光开关开关，并分析影响双稳光开关的各种因素。