An autocloned photonic crystal with a three dimensional periodic structure, can be fabricated as a 1D periodic structure in the direction of deposition, deposited on a 2D patterned substrate. However, it is very difficult to obtain the unique optical characteristics obtained by a three dimensional periodic structure consistently. To fabricate such a unique structure consistently, we have developed an element that consists chiefly of a unit cell that is a 2D structure.
An autocloned photonic crystal of two dimensions functions as an anisotropic optical multilayer film, and can achieve familiar functions such as that of a polarizer or wave-plate. There are three degrees of freedom during design; the choice of the optical materials used, the depth of the pattern of the substrate, the thickness of the films (pitch of the structure) by appropriate choice of which a polarizer or wave-plate can be fabricated. Moreover, it is possible to improve the extinction ratio of the polarizer by for instance increasing the number of layers deposited. Accurate control of the retardance of a wave-plate is possible by fine-tuning of the film thickness. In principal any material suited to sputtering deposition can be freely chosen. Typical substrate materials are quartz, optical glasses, and Si.
Because the final layer to be deposited on the photonic crystal results in a flat surface, Autocloned photonic crystals can be handled (cleaned) in the same way as conventional multilayer films.