3.9-4.8 μm gain-switched lasing of Fe:ZnSe at room temperature

We report a room temperature Fe:ZnSe laser in gain-switched operation and tuning over the 3.9-4.8 mu m spectral range. Mid-IR emission of Fe2+:ZnSe was studied under three regimes of excitation: ordinary optical (2.92 mu m) excitation of T-5(2) excited state of Fe2+; excitation via E-5 level of Cr co-dopant (1.56 mu m); and excitation via photo-ionization transition of Fe2+ (0.532 mu m). The energy transfer from Cr2+ (E-5 level) to Fe2+ (T-5(2) level) under 1.56 mu m wavelength excitation was observed and resulted in simultaneous room temperature emission of Fe: Cr: ZnSe crystal over ultra-broadband spectral range of 2-3 and 3.5-5 mu m. We also report the observation of mid-IR emission at 3.5-5 mu m induced by 2+-> 3+-> 2+ ionization transitions of the iron ions in Fe:ZnSe. (c) 2005 Optical Society of America.