Nonlinear photonic crystal

Nonlinear photonic crystals are usually used as quasi-phase-matching materials. They can be either one-dimensional^[1] or two-dimensional.^[2]

Nonlinear Photonic Crystals

Broadly speaking, nonlinear photonic crystals (PC) are periodic structures whose optical response depends on the intensity of the optical field that propagates into the crystal. An immediate consequence is that such structures have new optical properties with improved or new functionalities that cannot be obtained by using their linear counterpart, namely linear pPCs. One such example is optical tunability, that is, optical control of the response of devices based on PC. Although tunability of optical properties of photonic crystals can be achieved, for instance, by applying an electric field to an inverse opal PC infiltrated with nematic liquid crystal, by modulating the PC's index of refraction through the electro-optic effect induced by an external electric field, or through temperature-induced changes in the PC's index of refraction, high-speed operability desired for certain advanced optical communication systems can be obtained only if intrinsic optical nonlinearities in the PC material are employed. The reason for this is the ultra-fast response of certain nonlinear dielelectric materials to optical fields. In contrast to the now very extensive body of research in the properties and devices in linear photonic crystals, research into the theoretical and experimental behavior of these structures under conditions of intense optical fields, e.g. in the nonlinear regime, is still in its formative stages.

References

http://cumsl.msl.columbia.edu/optics/nicolae/NonlinPhotCryst.html