Two-tunable-frequency microlasers passively Q-switched by Cr/sup 4+/:YAG

Summary form only given. Diode laser-pumped solid-state lasers passively Q-switched by Cr/sup 4+/:YAG are the subject of a growing interest due to their numerous potential applications. Besides its spectroscopic properties which make it a good saturable absorber for Nd:YAG lasers, Cr/sup 4+/:YAG exhibits peculiar properties with respect to the polarization of the absorbed radiation: its transmission is isotropic in the small signal regime but becomes anisotropic in the saturation regime. This often leads to linearly polarized output when quasi-isotropic microchip lasers are considered. However, peculiar regimes with alternate polarization states in the pulse train are commonly observed and hardly controlled. Here we show experimentally and theoretically how doubly polarized pulses can be emitted from such lasers, in alternate or simultaneity regimes.