New Nonlinear Sol−Gel Films Exhibiting Photorefractivity

Abstract

The first photorefractive sol−gel film has been prepared by copolymerization of tetraethoxysilane and modified silane monomers having push−pull azobenzene and carbazole moieties. Thin films poled by corona discharge exhibited large quadratic nonlinearities (electrooptic coefficient r33 ≈ 17 pm/V, at 633 nm). Preliminary two-beam coupling measurements, without applying external electric field, showed photorefractivy of this new sol−gel material.