CR4+/YAG AS PASSIVE Q-SWITCH FOR A ND-YALO OSCILLATOR WITH AN AVERAGE REPETITION RATE OF 2.7-KHZ, TEM(00) MODE AND 13-W OUTPUT

A conventional pulsed Nd:YALO oscillator was passively Q-switched with a Cr4+:YAG crystal. During each of the flashes, with a repetition rate of 100 Hz, a burst of 27 Q-switch pulses with a half width (FWHM) of 140 ns was generated. The minimal pulse-to-pulse time interval within the burst was about 5 mus. The average repetition rate of these Q-switch pulses was 27 x 100 Hz. Nd: YALO as active material does not show any thermally induced birefringence and therefore a good TEM00 mode was realized despite the high thermal load of the crystal. The 4 x 79 mm laser rod produced 13 W average output power at 1080 nm with an efficiency of 0.5%. In contrast to earlier used LiF:F2- absorbers as passive Q-switch the Cr4+:YAG-crystals did not bleach and therefore the system operated very stable and reliable.