Study on gain-switched Fe:ZnSe mid-infrared laser at room temperature

To construct a compact mid-infrared short-pulse laser light source capable of operating at room temperature, a gain-switching scheme was adopted, using an Er:YAG electro-optic Q-switched laser based on LiNbO₃ crystals as the pump source to excite Fe:ZnSe crystals. Relevant simulation analysis and experimental validation were conducted. The experimental findings demonstrated that the Fe:ZnSe laser achieved a maximum output energy of 1.37 mJ, with a slope efficiency of 20.8% with respect to the input pump energy. Furthermore, the output laser pulse demonstrated typical relaxation oscillation characteristics in the time domain. At a pump energy of 6.5 mJ, the laser pulse width was measured to be 78.2 ns, while the first pulse exhibited a delay of approximately 94.1 ns with respect to the pump pulse, with its minimum pulse width reaching 2.2 ns. The simulation results, derived from rate equation group theory, were generally consistent with the experimental results, thus providing theoretical support for optimizing the laser design. These research findings can provide valuable insights for obtaining high-energy short-pulse lasers in the mid-infrared band at room temperature.