Understanding and eliminating photovoltaic induced instabilities in contra-directional two-beam coupling in photorefractive LiNbO3:Fe

Abstract In contra-directional two-beam coupling using photorefractive reflection gratings in LiNbO 3 :Fe, noise is observed in the form of quasi-periodic temporal instabilities. These instabilities result from different mechanisms that affect the magnitude of the space-charge field, and are attributed to the strong photovoltaic field generated in LiNbO 3 :Fe. A method of coating the z -surfaces of the crystal with a semi-transparent conductive coating eliminates these instabilities.