利用非线性薛定谔方程(NLSE)为2 μm掺Tm3+自相似脉冲激光器建立了一种新的数值模型。模型中, 用NLSE描述脉冲在激光器中的产生和传播, 利用MATLAB软件模拟了脉冲在激光腔内的演化特性, 优化了腔内净色散、增益系数和可饱和吸收体等参数, 得到了典型的2 μm自相似脉冲的产生区域和特点。在最佳运行范围内, 通过仿真得到了能量为7.87 nJ、脉宽为30.58 ps的具有严格正啁啾的高功率抛物线型脉冲。同时, 分析了腔内净色散、增益系数和可饱和吸收体等参数对自相似脉冲产生的影响, 并模拟了光栅器件进行色散补偿, 使输出脉宽达到547 fs, 脉冲峰值功率达到20.85 kW。本文为获得高功率自相似脉冲提供了指导性意见。

A new numerical model for a 2 μm thulium-doped self-similar pulsed laser was established using nonlinear Schrdinger equation (NLSE). In this model, NLSE was used to describe the generation and propagation of the pulse in the laser. The evolution of the pulse in the laser cavity was simulated using MATLAB software. The parameters such as the net dispersion, the gain coefficient and the saturable absorber were optimized. The typical 2 μm self-similar pulse generation area and characteristics were obtained through simulation. In the optimal operating range, a high-power parabolic pulse with strict positive chirp with the energy of 7.87 nJ and the pulse width of 30.58 ps was obtained. At the same time, the effects of parameters such as the net dispersion, the gain coefficient and absorber on the self-similar pulse were analyzed. We simulated the grating for dispersion compensation. The output pulse width reached 547 fs and the pulse peak power reached 20.85 kW. This paper gives guidance for obtaining high-power self-similar pulses.