Polarization properties of laser-diode-pumped micro-grained Nd:YAG ceramic lasers

Detailed polarization properties have been examined in laser-diode-pumped (LD-pumped) micro-grained ceramic Nd:YAG lasers in different microchip cavity configurations. Stable linearly-polarized single-frequency oscillations, whose polarization direction coincides with that of an LD pump light, were observed in an external cavity scheme. In the case of a thin-slice laser scheme with coated reflective ends, elliptically-polarized single-frequency operations took place in the low pump-power regime and dynamic modal instability appeared with increasing the pump power, featuring self-induced antiphase modulations among counter-rotating circularly-polarized modes having slightly different frequencies, with the total output being stabilized