Low-magnification unstable resonators used with ruby and alexandrite lasers.

Low-magnification unstable resonators that utilize radially birefringent elements and that have been shown to be suitable for use with ruby and alexandrite lasers are described. From these resonators, 400 mJ of energy in a Q-switched pulse with ~2.5x diffraction-limited output has been obtained from alexandrite, and 250-mJ Q-switched output that is near diffraction limited has been obtained from ruby.

Tunable-laser performance in BeAl(2)O(4):Cr(3+).

Broadly tunable laser operation has been obtained at room temperature from the vibronic bands of single-crystal BeAl(2)O(4):Cr(3+) under Xe-flashlamp excitation. Continuous tuning is obtained from 701 to 794 nm, with maximum power at 750 nm. Long-pulse operation employing 6.3-mm x 76-mm rods easily provides 500 mJ in 200-microsec bursts, whereas 70-mJ, 120-nsec pulses are obtained under Q-switch operation.