Self-pumped four-wave mixing (SPFWM) mediated by backward stimulated Brillouin scattering (SBS) has been described previously.1 SPFWM by forward SBS occurs in an exactly analogous manner. An optical resonator is constructed coaxially with a light pipe. When optical radiation Is injected into the light pipe at an angle Θ to the axis, some light is scattered off acoustic noise into the optical cavity. If the angle of scattering Is obtuse (acute), the scattering is in the forward (backward) direction. On each round trip in the cavity, the scattered light is amplified by the Brillouin gain provided by the input beam in the SBS medium. The radiation in the optical cavity appears as two coun- terpropagating beams, phase conjugate to each other. These two beams interact with the input beam in a nearly degenerate four-wave mixing process mediated by SBS, resulting in a phase conjugate beam.
© 1989 Optical Society of AmericaPDF Article