Room temperature sub-nanosecond Fe:ZnSe gain-switched laser characterization and modeling

Sub-nanosecond mid-IR lasers are essential for applications like optical parametric amplification and material processing, yet effective sources are limited. This study explores room temperature gain-switched (GS) Fe:ZnSe lasers at 4.4–4.6μm, focusing on spike-like oscillation dynamics to generate sub-ns pulses from 9ns KTA-based OPO pump pulses. We suppressed relaxation oscillations by optimizing cavity length, gain element length, and output coupler reflectivity for single-pulse oscillation regime and obtained single-pulse GS operation. Numerical approximation predicted an output pulse with 850ps pulse duration. Experimentally, single-spike oscillation yielded output energy as high as 1.05mJ (Δt = 841ps) with 16mJ pumping from the 2.98μm KTA-OPO idler. This corresponds to a peak power of 1.25MW. These findings demonstrate the potential of Fe lasers for high-energy, ultra-short pulse generation in the mid-infrared range.