Temperature dependence of Fe:ZnSe mid-infrared spectral and laser output properties under ∼4 μm radiation excitation

This paper presents the temperature dependence of the spectroscopic and laser properties of the Fe2+:ZnSe single crystal under excitation by radiation at a wavelength of similar to 4.04 mu m. Excitation was supported by the Er:YAG laser (similar to 2.94 mu m) operated in the Q-switched or free-running (FR) mode that pumped the Fe:ZnSe laser cooled by liquid nitrogen to 78 K. This system generated radiation at the wavelength of similar to 4.04 mu m. Temperature dependence of absorption, fluorescence spectra, and fluorescence decay time of Fe2+ ions was measured. The optimal temperature that allows efficient Fe:ZnSe laser system operation with maximum laser output energy was sought in both regimes. It was characterized at a repetition rate of 1Hzwith pulse durations of similar to 175 ns and similar to 155 mu s in both modes, respectively. The highest laser output energies obtained with the crystal placed in the cryostat in gain-switched (GS) and FR modes were similar to 385 mu J at 260 K and similar to 374 mu J at 190 K, respectively. Maximum optical-to-optical efficiencies in the same modes were similar to 13% at 260 K and similar to 32% at 170 K, respectively. Wide laser radiation oscillation spectra depending on the temperature ranging from similar to 4.3 mu m at 140 K to similar to 4.9 mu m at 340 K obtained with a Gaussianlike beam spatial profile were demonstrated. Under atmospheric conditions at RT, this laser system reached a pulse energy of over 0.5 mJ at similar to 4.78 mu m in similar to 135 ns pulses, which corresponds to a peak power of similar to 3.9 kW. (c) 2024 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.