Guiding effects in Nd:YVO4 microchip lasers operatingwell above threshold

摘要

Guiding of the transverse mode in Nd:YVO4 microchipnlasers is examined both experimentally and theoretically at pump powersnwell above threshold. It is found that thermal changes in the cavityngeometry induced by intense diode pumping can be well understood using ansimple model. However, an understanding of these effects is notnsufficient to explain the nature of the transverse mode. Gain-relatednguiding effects are found to play an important role even at pump powersnwell above threshold. For a 0.5-mm-thick microchip laser, a differencenof around 30% is observed between the minimum beam waist expected due tonthermal guiding and the measured beam waist. The gain-related effectsnare described theoretically and their importance is demonstratednexperimentally