Infrared Photorefractive Polymers and Their Applications for Imaging

Photorefractive polymers with high diffraction efficiency in the visible and near-infrared regions of the electromagnetic spectrum have been developed. These polymers, which have a large dynamic range because of their high orientational birefringence, incorporate a dye designed to have a large dipole moment and a high linear polarizability anisotropy. Such polymers have enabled demonstrations of imaging through scattering media, using a holographic time-gating technique at a wavelength that is compatible with the trans-parency of biological tissues and with the emission of low-cost semiconductor laser diodes. The photorefractive (PR) effect enables the recording of optical information in three-dimensional solids through the opti-cal generation of an internal space-charge field that gives rise to refractive index changes in the material (1, 2). Because of their high optical sensitivity and the abilit