<title>Applicability of the band transport (Kukhtarev) model to photorefractive polymers</title>

Abstract

The band transport model of space-charge production has proved very successful in describing photorefractive phenomena in a wide range of inorganic crystals, ranging from high-mobility semiconductors like GaAs, to highly insulating ferroelectrics like BaTiO<SUB>3</SUB>. This success is primarily due to the applicability of a generic picture of charge transport in extrinsic crystalline semiconductors, a picture that becomes cloudy in noncrystalline systems like the new photorefractive polymers. Photorefractive polymers exhibit the classic photorefractive behaviors such as photoconduction, electro-optic response, hologram formation and storage, and two-beam energy coupling, all without benefit of a crystalline lattice or well defined conduction band. In this report, I will outline how the band transport model can be adapted to describe photorefraction in noncrystalline materials by the dual expediencies of renaming certain embarrassing 'constants' and admitting that they are strongly dependent on the total electric field.