Wave Mixing in Photorefractive Polymers: Modeling and Selected Applications

Abstract

This chapter summarizes our work in the area of photorefractive polymers, a material which can be engineered to specifications for potential applications to holography, 3D displays, and energy exchange through two-wave mixing. In usual photorefractive polymers, holes are the primary mobile carriers which give rise to the electrostatic field and the induced refractive index. After a brief introduction to the material equations for modeling the photorefractive effect in the steady state, the phase shift between the intensity grating and the induced refractive index grating is discussed in detail. The material equations, in conjunction with the optical propagation equation, is next used to describe two-wave mixing leading to energy exchange in the material, taking into account the effect of beam fanning. Generation of higher non-Bragg orders is also considered, particularly in light of its potential applications to image processing. Examples of image processing such as edge enhancement, image correlation, and adaptive filtering are discussed. Finally, the transient response of these materials is considered, and it is shown that in addition to holes, there may be contributions from electrons over a range of applied bias fields, which can compromise the two wave coupling gain of the polymer.