Techniques for high-power laser array beam combination processes involving photo-refractive materials are reviewed. Details of an all semiconductor laser scheme for the amplification and subsequent photorefractive beam clean-up of a diffraction limited single-mode laser output is presented. Powers in excess of 100 mW (>220 mW accounting for Fresnel losses) are obtained in a diffraction limited signal beam, corresponding to an array to diffraction limited beam transfer efficiency of 33%. Details of a reflection geometry phase conjugate master oscillator-power amplifier scheme which offers the possibility of power scaling between a number of high-power semiconductor laser amplifiers are presented. Using this technique, a 13-dB amplification of a diffraction limited signal beam is obtained using a commercially available, 10-stripe gain-guided device with no special coatings.
PHOTOREFRACTIVE TECHNIQUES FOR DIODE LASER BEAM COMBINATION
