ALL-SOLID-STATE DIODE-PUMPED ND-YAG MOPA WITH STIMULATED BRILLOUIN PHASE-CONJUGATE MIRROR

At the Nederlands Centrum voor Laser Research (NCLR) a 1 kHz diode-pum ped Nd:YAG Master Oscillator Power Amplifier (MOPA) chain with a Stimu lated Brillouin Scattering (SBS) Phase Conjugate mirror is designed an d operated. A small Brewster angle Nd:YAG slab (2 by 2 by 20 mm) is si de pumped with 200 mu s diode pulses in a stable oscillator The oscill ator is e-switched and injection seeded with a commercial diode pumped single frequency CW Nd:YAG laser. The output consists of single-trans verse, single-longitudinal mode 25 ns FWHM-pulses at 1064 nm. The osci llator slab is imaged on a square aperture that transmits between 3 an d 2 mi (at 100 and 400 Hz, resp.) The aperture is subsequently imaged four times in the amplifier. The amplifier is a 3 by 6 by 60 mm Brewst er angle zig-zag slab, pumped by an 80-bar diode stack with pulses up to 250 mu s. After the second pass the light is focused in two consecu tive cells containing Freon-113 for wave-front reversal in an oscillat or/amplifier-setup with a reflectivity of 60%. The light then passes t hrough the amplifier twice more to produce 20 W (at 400 Hz) of output with near diffraction limited beam quality. To increase the output to 50 W at 1 kHz thermal lensing in the oscillator will be reduced.