SPECTROSCOPIC AND TUNABLE LASER PROPERTIES OF CO2+-DOPED SINGLE-CRYSTALS

We present here a comparison of the general optical properties (absorptions, emissions, fluorescence decays) of various Co2+-doped single crystals (KZnF3, KMgF3, MgF2, and MgO) and the results of direct measurements of excited-state-absorption (ESA) cross sections and of laser experiments in Co2+-doped KZnF3 and MgF2. The ESA measurements are made in the pump as well as in the emission domains. The data are interpreted, with some approximations, within the framework of the single-configurational-coordinate model and the Struck and Fonger formalism. The laser data (threshold, efficiency, and tunability) are obtained at room temperature and in the same pumping conditions (pulsed-type longitudinal pumping) for the two systems. It is shown that MgF2:Co2+, in spite of a stronger ESA at the usual pumping wavelength of 1.32 mum, leads to better laser performance than KZnF3:Co2+ and that the fluorescence quantum efficiency of both systems is quite low.