ABSTRACT
The bulk of the index contrast in high-performance photorefractive polymers is due to the alignment of dipolar chromophores toward the local field direction within the material. The form of the index contrast transient observed is therefore strongly dependent on the dynamic reorientational response of the chromophores to changes in the local electric field. (The total field at any point in a photorefractive sample is the resultant of the field applied externally and the spatially varying space-charge field formed by the photorefractive effect.) A good understanding of chromophore rotational response not only allows a meaningful assessment of holographic formation speed and intercomparison of materials but it also allows the physical processes that underlie photorefraction, such as charge generation and transport, to be more readily investigated. Moreover, knowing the form of the index transient is useful in the rational design of many applications of photorefractive polymer composites. For instance, hologram multiplexing in a data storage device requires an understanding of the index growth dynamic so that hologram writing can be efficiently scheduled.
