Optical triggering of a Q-switched Nd:YAG laser via transverse bleaching of a Cr:YAG saturable absorber

Optical triggering via direct bleaching of a Cr:YAG saturable absorber was applied to a monolithic Nd:YAG/Cr:YAG laser crystal. The method uses a single laser diode bar to bleach a thin sheet within the saturable absorber from a direction orthogonal to the lasing axis. By placing the Q-switch at the time corresponding to the steepest slope (dT/dt) for change in transmission during bleaching, the pulse-topulse timing jitter showed a 13.2x reduction in standard deviation, from 132 ns for free-running operation to 10 ns with optical triggering. We measured that a fluence of 60 kW/cm(2) was sufficient to enable optical triggering, where a diode appropriately sized for the length of the Cr: YAG (similar to 3 mm) would then require only similar to 150 W of optical power over a 1-2 mu s duration to enable effective jitter reduction. Additionally, we measured an increase in optical-to-optical efficiency with optical triggering, where the efficiency improved from 12% to 13.5%. (C) 2009 Optical Society of America