Two-Wave Mixing in Saturable Absorbers and Ranging Applications

Abstract

When two coherent light beams overlap in a saturable absorber, the materials refractive index is altered in phase with the light intensity distribution and a volume phase and/or absorption grating is created. A frequency shift introduced on one of the beams causes the fringe pattern to move. In materials with a finite response time, τ, a phase lag between the grating and the intensity pattern is produced and exchange of energy between the beams can occur.