Photoconductive and electro-optical Properties of Hf-doped Lithium Niobate Crystals

The optical and electrical properties of a set of Hf doped Lithium Niobate crystals with doping level from 2 to 8 mol % are reported. The photoconductivity is found to increase remarkably for Hf concentration equal and above 4 mol %. In contrast, the electro-optical coefficients keep almost constant with the crystal structural properties preserved. The conclusion is drawn that the decrease of the photorefractive response in Hf doped Lithium Niobate recently observed by other authors is mainly related to the increased photoconductivity.