Phase conjugate mirror

With an ordinary mirror, the image is reflected rather than redirected. Phase conjugate mirrors can be constructed to provide a number of lensless imaging and image-processing functions. Current values of electronic non-linearities in polymers require laser power densities in the range of kilowatt per square centimeter in order for these effects to be manifested. Photo-refractive materials such as BaTi03 crystals have been used to demonstrate these effects at a power density of approximately 10 mW/cm (12),... 

Fig. 3.8 The reflection of a ray of light off an ordinary mirror and off a phase conjugate mirror.

Shin JS, Park S, Kong HJ (2010) Compensation of the thermally induced depolarization in a double-pass Nd YAG rod amplifier with a stimulated Brillouin scattering phase conjugate mirror. Opt Common 283 2402-2405... 

These mirrors may be regarded as one-dimensional holograms that are generated when a chirped and an unchirped laser pulse from opposite directions are superimposed in a medium where they generate a refractive index pattern proportional to their total intensity [693]. When a chirped pulse is reflected by such a hologram, it becomes compressed, similar to the situation with phase-conjugated mirrors. 

For example, the phase conjugate operation is of particular interest in optical systems." In identifying the wavefront phase distribution y), a phase conjugate operation produces a counterpropagating wave with opposite phase — (x,y). Therefore, it is possible to construct systems where the phase aberrations are automatically cancelled by a double pass through the distorting media via a phase conjugate mirror. 

H. Rajbenbach and J. P. Huignard, Self induced coherent oscillations with photorefractive Bi,2Si02o amplifier, Opt. Lett., vol. 10, pp. 137-139, 1985 J. Feinberg and R. W. Hellwarth, Phase-conjugating mirror with continuous-wave gain, Opt. Lett., vol. 5, pp. 519-521, 1980. 

The availability of nonlinear optical materials has opened up new possibilities in interferometry. One such involves the use of a nonlinear optical material as a phase-conjugate mirror (PCM). 

Cronin-Golomb, M., B. Fisher, J. O. White, and A. Yariv. 1983. Passive phase conjugate mirror based on self-induced oscillation in an optical ring cavity. Appl. Phys. Lett. 42 919. 

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