Recovery of laser beam propagation through a turbulent amplifier using phase conjugation

Abstract

The recovery of an optical beam, distorted by a turbulent medium with random gain (loss), using phase conjugation is investigated. Turbulence broadens the beamwidth and the random gain enhances the broadening effect. Meanwhile, the backscattering enhancement effect occurs because 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. The enhancement backscattering effect is stronger for a PCM than for the conventional mirror. It is found that when the random gain exists, the enhancement effect is enhanced and becomes stronger when either the characteristic length or fluctuation strength of active molecule number density of the turbulent medium is increased. The average reflected beam intensity is evaluated using the path integral technique.