Cr/sup 4+/:YAG as passive Q-switch and Brewster plate in a pulsed Nd:YAG laser

We demonstrate the performance of a Nd:YAG laser, passively Q-switched with a Cr/sup 4+/:YAG plate, which plays the double role of a passive Q-switch and a Brewster plate. The Brewster plate configuration contributes an intracavity loss of approximately 3.2-10/sup -3/ cm/sup -1/ along the cavity length. Losses contributed by the active Cr/sup 4+/ ions in the plate relate to their excited state absorption. A freshly measured transmission saturation curve of Cr/sup 4+/:YAG suggests a ground state absorption cross section /spl sigma//sub gs/=(8.7/spl plusmn/0.8)-10/sup -19/ cm/sup 2/, and an excited state absorption cross section /spl sigma//sub es/=(2.2/spl plusmn/0.2)-10/sup -19/ cm/sup 2/ of the Cr/sup 4+/ ions at /spl lambda/=1064 nm.<
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