Conditions for Efficient Build-Up of Power in a Ring-Cavity with Rh:BaTiO/sub 3/

Numerous interaction geometries have been developed for photorefractive materials that rely on amplification of light via the two-beam coupling effect. One of the most elegant and simple configurations is a unidirectional ring resonator, which consists of a photorefractive crystal placed in a ring cavity and pumped by an external beam. If the two-beam coupling gain is above threshold, the resonating beam will build up from the amplification of scattered light. We present results on the most crucial parameters for the effective build-up of power in the resonating beam the wavelength of the pump beam, and the type of photorefractive material. The resonating beam accumulates energy from successive amplification in a photorefractive material until saturation sets in but also loses energy from absorption and other losses such as Fresnel reflections from the crystal and imperfect mirrors. We have performed intensity-dependent modelling of the resonator's power conversion factor. The power conversion factor is defined as the ratio of the resonating beam intensity to the intensity of the external pump beam. The figure below shows the dependence of this factor on absorption coefficient for different values of coupling coefficient Gamma.