THERMAL LENS DETERMINATION OF END-PUMPED SOLID-STATE LASERS USING PRIMARY DEGENERATION MODES

A simple method using the singularities of an optical resonator to det ermine the thermal lens of end-pumped laser crystals is reported in th is letter, At certain resonator parameters the transverse structures o f the laser beam become a superposition of many transverse cavity mode s of equal resonance frequencies. Because the resonator parameters dep end on the thermally induced lens in the active medium, the strength o f the lens can be determined by means of measuring the shift of the de generation resonator length depending on the pumping power, The method is applied to an end-pumped Nd:YAG laser. (C) 1997 American Institute of Physics. [S0003-6951(97)01844-5].