Coherent coupling of laser gain media using phase conjugation

A laser energy-scaling technique, based on a phase-conjugate oscillator/amplifier scheme that permits the coupling of several parallel amplifiers to form a single coherent output beam has been demonstrated experimentally. This coherence is achieved despite dramatic differences in the individual amplifier energies and optical path lengths. When many amplifiers are coupled together, energy can be scaled significantly beyond the limit imposed by the maximum available volume of a single active medium. Although the present demonstration utilized Nd:YAG, this technique is quite general and can be applied to a variety of laser media.