Fabrication experiment of photorefractive three-dimensional waveguides in lithium niobate

A technique for fabricating optical waveguides in a lithium niobate crystal is studied experimentally. We fabricate straight and curved structures of refractive index as the optical waveguides in a volume of the photorefractive crystal by scanning a focused laser beam. The experimental results show that the structure of refractive-index distribution is complex yet imply guiding of light in the part of high refractive index within the fabricated structure.