100-WATT AVERAGE OUTPUT POWER 1.2 DIFFRACTION-LIMITED BEAM FROM PULSED NEODYMIUM SINGLE-ROD AMPLIFIER WITH SBS PHASE-CONJUGATION

We describe a solid-state master oscillator-amplifier laser (MOPA) with a minimum number of elements for the double-pass single-rod amplifier, It produces 100-W average output power of pulsed light with an almost diffraction limited beam, The and-switched system works with an average repetition rate of about 3 kHz and the pulse width was 70 ns. As active material we used Nd:YALO (Nd:YAP) which has negligible depolarization. The strong thermal lens of the material with focal lengths of less than 15 cm at pump powers of 8 kW was compensated by a phase conjugating mirror based on stimulated Brillouin scattering (SBS), Therefore, the output power could be varied from 2 W up to 100 W without changing the transversal beam profile. The total efficiency of the amplifier including the phase conjugator is 1.25%.