基于新型二维纳米材料饱和吸收体双损耗调制的中红外2μm波段激光特性研究

All- solid-state at mid-infrared 2μm waveband region are of impotant applications in the fields such as ranging, laser LIDAR, medical treatment, materical processing, optical communication and so on. Novel two-dimentional nano-materials, such as grapheme, black phosphorus, transition-metal dichalcogenides, etc., are of excellent saturated absorption characteristics of broadband saturable modulation, low saturated intensity, controllable modulation depth, ultrafast recovery time and so on, and have been achievelly used in single-loss-modulated mid-infrared 2μm waveband laser systems. Generally speaking, no matter active-modulation or passive-modulation, it is very difficult for single-loss-modulated lasers at 2μm waveband region to have short pulse width, great peak power and high stability at the same time. Dual-loss-modulations can benefit from the advantages of two loss-modulations efficiently, obtain shorter pulse width，higer peak power and higher stability. This project will use two kinds of loss-modulation technology based on the saturable absorbers of novel two-dimentional nano-materials, i.e. the active modulation and the the passive saturated absorption of the saturable absorbers, to realize LD-pumped Q-switched and Q-switched mode-locked laser run, probe the generation mechanism of mid-infrared 2μm lasers based on dual-loss-modulation, reveal the basic generation principle of dual-loss-modulated 2μm lasers with, high peak power, short pulse width and high stability, investagate their run laws, stability and parameter optimization characteristics. From the abovementioned studies, the law basis and the application prospects of dual-loss-modulation technology in mid-infrared 2μm lasers will be presented.

全固态中红外2μm波段激光在测距、激光雷达、医学诊治、材料处理、光通信等领域具有重要的应用。新型二维纳米材料饱和吸收体，如石墨烯、黑鳞、过度金属二硫属化物等，具有饱和调制波段宽、饱和光强低、调制深度可控、恢复时间快等优良特性，已成功应用于中红外2μm波段激光系统中。通常单损耗调制的2μm波段激光，不论是主动调制还是被动饱和吸收，均难以同时兼顾窄脉宽、高峰值功率、高稳定性等。双损耗调制技术可以有效结合两种损耗调制的优点，能获得脉宽更窄、峰值功率更高、稳定性更强的激光。本项目拟将主动调制、新型二维纳米材料饱和吸收体被动吸收相结合，实现双损耗调制2μm波段激光运转，探索基于双损耗调制的中红外2μm波段激光产生的机理，揭示双损耗调制的高峰值功率、窄脉宽、高稳定2μm波段激光产生的基本原理，研究双损耗调制的2μm波段激光的运转规律和参数优化特性，为双损耗调制技术在中红外波段激光的应用提供规律性依据。

采用热聚合、液相剥落、CVD、旋转喷涂等方法，制造了二维纳米材料g-C3N4、MoS2、WS2、MXene Ti3C2Tx、Sb2Te3、VS2、Ta2NiS5、Ta2NiSe5、MoWS2、Bi2Te3、MoSe2、FONPs、GNPs等，表征了它们的形貌，测量了它们的饱和吸收特性；从理论和实验上系统地研究了基于二维纳米材料饱和吸收体双损耗调制的中红外2μm波段调Q和调Q锁模激光特性，实现了二维纳米材料饱和吸收体（g-C3N4、MoS2、WS2、MXene Ti3C2Tx、Sb2Te3、VS2等）——主动（声光和电光）双调Q激光运转、二维纳米材料饱和吸收体（Ta2NiS5——Ta2NiSe5、MoS2—WS2）双被动调Q激光运转、二维纳米材料饱和吸收体MoWS2——主动电光双调Q锁模激光运转，获得了稳定的双损耗调制中红外2μm波段激光输出。定义了脉宽的压缩比（单调制脉宽/双调制脉宽）和峰值功率增强因子（双调制峰值功率/单调制峰值功率）描述双损耗调制激光的特性，与单一调制的激光相比，双损耗调制激光能够获得脉冲宽度更窄、脉冲能量更大、峰值功率更高、稳定性更好的输出。理论上，建立了平面波近似下二维纳米材料饱和吸收体被动吸收——主动电光调制中红外2μm波段双调Q激光振荡的耦合速率方程组，数值求解方程组获得了调Q激光的脉冲宽度、脉冲能量、峰值功率与主动重复率、泵浦功率等参量的依赖关系，数值模拟与实验结果相符。 理论和实验的研究结果显示：二维纳米材料是中红外2μm波段激光优良的饱和吸收体，基于新型二维纳米材料饱和吸收体，利用双损耗调制技术是一种获得短脉冲、高峰值功率、高稳定2μm波段脉冲激光的有效方法。

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