AN 8.2 J-PHASE-CONJUGATE SOLID-STATE LASER COHERENTLY COMBINING 8 PARALLEL AMPLIFIERS

We describe a phase-conjugate master oscillator-power amplifier config uration in which as many as eight parallel flashlamp-pumped Cr:Nd:GSGG amplifiers and four parallel CD A frequency doubling crystals were c oherently combined. Operating at a pulse repetition frequency of 1.25 Hz, we demonstrated an output energy of 8.2 J at 1 mum and 4.4 J at 53 0 nm for a 54% frequency-doubling efficiency. This effort represents t he highest reported output energy achieved using coherent coupling via phase conjugation. In subsequent experiments at a pulse repetition fr equency of 5 Hz, we produced approximately 22 W of 1.06 mum average po wer with a beam quality that was approximately 2.5 times diffraction-l imited. The observed far-field intensity profile indicates that we ach ieved effective and consistent compensation of optical-path length dif ferences among the multiple parallel amplifiers and frequency-doubling crystals.