Reduction in timing jitter for a Cr:YAG Q-switched Nd:YAG laser

To address the issue of pulse-to-pulse timing jitter in a passively Q-switched Cr:YAG/Nd:YAG laser, we have developed a technique for optical triggering, where the energy from a single bar diode was used to bleach a thin sheet within the Cr: YAG saturable absorber from a direction orthogonal to the lasing axis. A strong anisotropy for bleaching effect was observed; with appropriate polarization of the bleaching light the transmission through the saturable absorber was increased from 45% to 63%. This technique was applied to a monolithic Cr:YAG/Nd:YAG laser operating under steady state conditions. By placing the Q-switched pulse at the time corresponding to the steepest slope for change in transmission during bleaching, which occurs similar to 1 mu s after the bleaching diode trigger, we measured an 12.5X reduction in the pulse-to-pulse timing jitter, from 100ns for free running operation to 8ns with optical triggering.