Spectroscopy and kinetics of the population of monoclinic KYb0.5Y0.43Tm0.07(WO4)2 crystals pumped by a pulsed Nd:YAG laser

The kinetics of pump radiation absorption and luminescence of monoclinic crystals of potassium-yttrium-ytterbium tungstate doped with thulium are studied. It is shown theoretically and experimentally that due to the 'excitation multiplication' caused by absorption of pump radiation from metastable states of thulium ions accompanied by cross-relaxation, above 50% of a total number of thulium ions can occupy the ³F₄ level. The cross sections of stimulated transitions in the spectral region from 1600 to 2100 nm are calculated from luminescence spectra, and the gain in the crystal is estimated. The prospects of practical applications of the results obtained in the paper are discussed.