Optical Oscillators with Photorefractive Gain

Abstract

Ferroelectric crystals with large electrooptic coefficients such as BaTiO₃and Sr_(1-x)Ba_xNb₂O₆(SBN) are able to support photorefractive holographic gratings with large diffraction efficiencies. These gratings form even with low power (≈1 W/cm²) beams in real time in such a way as to coherently amplify some of the writing beams at the expense of the others, making possible the construction of many kinds of optical parametric oscillators. Many of these devices are self-pumped phase conjugate mirrors and this accounts for much of the interest that they have generated in the optics community. The first part of this paper deals with a nonphase conjugating ring resonator. It is the simplest photorefractive oscillator and offers a good introduction to the more complex phase conjugating devices. We then proceed to a discussion of photorefractive phase conjugation, phase conjugate resonators and self-pumped phase conjugate mirrors.

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