Science and Applications of Photorefractive Polymeric Materials

In the past few years, a new class of polymeric materials for photonic applications has appeared called photorefractive (PR) polymers. Photorefractivity is defined as modulation of the index of refraction in an electro-optic material by internal electric fields produced by optical redistribution of charge carriers; hence it must not be confused with local mechanisms of index change such as photochromism, excited state population, heating, etc. When a material shows the required properties of charge generation, transport, trapping, and dependence of the index of refraction upon the internal electric field, it can be tested for photorefractivity by observation of asymmetric energy transfer (two-beam coupling) between two laser beams in the material.