利用分步傅里叶算法求解锥形半导体激光放大器中的稳态行波方程,对线性张角结构和非线性张角结构波导形状的激光放大器进行光学和热学性质的数值模拟。通过比较两种结构的激光放大器的输入电流-输出功率曲线,输入功率-输出功率曲线和光丝形成数量,研究放大器中光丝的形成机理,解释两种激光放大器中不同光场分布的原因。结果表明,非线性张角结构的放大器不仅能使增益分布和光场分布更契合,而且能减小波导边缘反射光和入射光的耦合,所以有着更高的光光转换效率和更稳定的模式输出。

Using the split-step Fourier method to solve the steady state traveling wave equation of tapered semiconductor laser amplifier, the optical and thermal characteristics of two kinds of laser amplifiers (with linear and nonlinear angle-opening structures) were analyzed by numerical simulation. By comparing the input current-output power curve, input power-output power curve and the number of filaments of the two laser amplifiers, the formation mechanism of filaments in the amplifiers was studied, and the reason of the different optical field distribution in the two laser amplifiers was explained. Results show that the nonlinear angle-opening structure can not only make the gain distribution more consistent with the optical field distribution, but also reduce the coupling between the reflected light and incident light at the edge of the waveguide. Furthermore, the tapered laser amplifier with nonlinear angle-opening structures has a higher optical-optical conversion efficiency and a more stable mode output.