Pump-induced bleaching of the saturable absorber in short-pulse Nd:YAG/Cr/sup 4+/:YAG passively Qswitched microchip lasers

Bleaching of the saturable absorber by pump light increases the length of the pulse generated in a passively Qswitched Nd:YAG/Cr/sup 4+/:YAG microchip laser and decreases the pulse energy. This effect is greatest when transmitted pump light is nearly focused in the Cr/sup 4+/:YAG and when pumping is sufficiently intense to bleach the absorption of the Nd:YAG. Both effects are important in short-pulse microchip lasers. The maximum repetition rate of a passively Q-switched Nd:YAG/Cr/sup 4+/:YAG microchip laser is correlated with the pulsewidth. In general, it decreases as the pulsewidth gets shorter.