Effects of pump heating on laser and spectroscopic properties of the Nd :[YAl3(BO3)(4)] self-frequency-doubling laser

In this work, thermal effects on the spectroscopic and laser properties of Nd:YAl3(BO3)(4) crystal caused by pump heating are systematically investiga ted. Changes in the refractive indices, absorption coefficient, and emissio n band shape have been studied in a temperature range 20-200 degrees C. Tem peratures up to 88 degrees C have been measured in a thermally isolated cry stal when pumping with 800 mW of laser power at 807 nm. A decrease in infra red laser power at 1.06 mu m and its second harmonic (0.53 mu m) generated by self-frequency doubling is observed during the early seconds of laser op eration. These reductions are explained in terms of the absorption efficien cy reduction and of thermal phase mismatch (for second harmonic) induced by pump heating. Instabilities observed in the output (infrared and green) la ser power during the initial seconds of laser action are satisfactorily exp lained in terms of Fabry-Perot-induced interference effects. (C) 2000 Ameri can Institute of Physics. [S0021-8979(00)03803-2].