Abstract

Nd:MgO:LiNbO₃ is a high gain solid-state laser material. In addition, it allows electronic control of the emitted radiation by virtue of its electrooptic properties. We have operated a miniature Q-switched laser consisting of a single 2- × 2- × 10-mm Nd:MgO:LiNbO₃ crystal and a Brewster plate placed between two mirrors spaced by 3 cm. This laser was end pumped by a dye laser beam at 598 nm. Peak powers of 5 W have been achieved with only 0.5% output coupling. Pulses 30-ns wide (FWHM) have been observed. The absorbed pump power threshold was 10 mW. Due to the material photoconductivity, an internal electric field can be generated that screens the external voltage. This screening effect was eliminated by applying the voltage in the form of pulses of alternating polarity. The voltage switching (from ~300 V to zero) excites several acoustic resonances in the crystal (piezoelectric effect) that modulate the crystal birefringence (elastooptic effect). The resulting time-dependent cavity loss affects the time of emission of the Q-switched pulse at low pump levels. However, the acoustic resonances have no influence when pumping more than three times above threshold.

© 1986 Optical Society of America