Recovery of laser beam in a turbulent amplifier by phase conjugation

The recovery of an optical beam, distorted by a turbulent medium with random gain (loss), by using phase conjugation has been investigated. Turbulence broadens the beamwidth and the random gain enhances the broadening effect. It is found that the optical beam cannot be totally recovered by phase conjugation due to the existence of random gain. Meanwhile, enhanced backscattering occurs since there is a coherent addition of the forward incident beam and the backscattered beam by a phase conjugate mirror (PCM). For comparison, the beam reflected by a conventional mirror is also considered. In the ease of PCM the enhanced backscattering is stronger than that of the mirror case. The average reflected beam intensity is evaluated by using the path integral technique. >