Fe2+-doped CdSe single crystal: growth, spectroscopic and laser properties, potential use as a 6 µm broadband amplifier

Abstract

We report on the successful growth of single crystals of Fe2+:CdSe by seeded physical vapor transport (SPVT) technique with doping within the growing process and subsequent annealing in Se vapor. Luminescence lifetime measurements, spectroscopic studies of 5E–5T2 transition of Fe2+ in CdSe, and laser experiments were performed. The lifetime of the 5T2 energy level was measured to be 20 ± 5 ns at a room temperature (RT) of 290 K. At liquid nitrogen (LN) temperature, luminescence kinetics displayed a non-exponential decay, which can be fitted to a bi-exponential function with time constants τ1 = 6 µs and τ2 = 29 µs. As much as 3.2 mJ of output energy at 5.2 µm with 27% absorbed pump energy slope efficiency of an Fe2+:CdSe laser was achieved at RT under 2.94 µm nanosecond Er:YAG laser pumping. The Fe2+:CdSe laser was tuned from 4.63 to 6.10 µm. Obtained characteristics of Fe2+:CdSe indicate that the crystal can be considered a promising medium for amplification of femtosecond pulses in the middle infrared range up to 6 µm.