Investigation of mechanically Q-switched lasers

Using a resonant scanner mirror Q-switch to provide a time varying change in cavity alignment, 1535nm lasers based on Er/Yb-doped glass and 1064nm lasers based on Nd:YAG were evaluated. Using a side pumping architecture, the Er/Yb glass laser used a compact mechanical Q-switch with a mirror rotation rate of 330 Rad/s, enabling generation of >3 mJ pulses with a pulse width of 16ns. The laser output was a diffraction limited TEM00 mode. A mechanical Q-switch based on a MEMS tilting mirror was also used; its performance in a laser cavity was found to be similar to the resonant mirror. The technique of mechanical Q-switching was also extended to a side pumped Nd: YAG laser (mirror sweep rate of 1300 Rad/s), enabling generation of Q-switched pulses of >30mJ and 25ns duration. The far-field divergence showed this laser to be highly multi-moded within the pump plane, with a measured beam-product-parameter greater than 30 mm-mRad.