V. I. Safonov

Beam and fiber coupler by phase conjugation

A scheme of light coupling into optical fiber was proposed and studied theoretically. Light coupling is realized by excitation of photorefractive oscillator. It consist of fiber facet and phase conjugate mirror based on four wave mixing. The scheme is self-adaptive and can tolerate rather large angular and lateral displacement of fiber end. As a result of numerical simulation we obtain that about 50 percent of reading pump wave intensity can be injected into the fiber. Coupling efficiency is decreased by factor of two when the lateral displacement of fiber end about 1000 micrometers .

Three- and four-wave forward amplification in AC fields

Forward three- and four-wave mixing in a photorefractive crystal are studied theoretically for the case of an AC field applied to the crystal and illuminated by a standing or moving interference pattern. The gain coefficients are obtained in the undepleted pump approximation. A comparison is made of the forward wave gain for the different mechanisms of signal beam amplification.

Subharmonic Generation by Phase Modulated Light Beams and AC Field

Generation of spatial subharmonic gratings in photorefractive crystal under an external AC field and a phase modulated interference pattern is investigated. This method of grating formation can lower the threshold contrast mth for the subharmonic generation.

Recording of photorefractive holograms by an AC field perpendicular to the grating vector

Static grating recording in photorefractive crystals by means of a running interference pattern and an AC field directed parallel to the fringes of the interference pattern is studied both theoretically and experimentally.

Phase-locked detection mechanism in photorefractive waveguides

Abstract The mechanism of recording a static grating in a planar photorefractive waveguide by a moving interference pattern and an external ac electric field is discussed. The direction of the external field is perpendicular to the waveguide layer. The recording efficiency is studied theoretically.