CR4+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 Cr4(+):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 x 10(-3) cm(-1) along the cavity length. Losses contributed by the active Cr4+ ions in the plate relate to their excited state absorption. A freshly measured transmission saturation curve of Cr4+:YAG suggests a ground state absorption cross section sigma(gs) = (8.7 +/- 0.8) x 10(-19) cm(2), and an excited state absorption cross section sigma(es) = (2.2 +/- 0.2) x 10(-19) cm(2) of the Cr4+ ions at lambda = 1064 nm.