Two-Dimensional Photonic Crystals

Abstract

Fabrication of two-dimensional (2D) photonic crystal (PC) samples is relatively easy compared to that of 3D PCs. Moreover, calculation of the band structure is also far easier. Although a full band gap does not exist in a strict sense, 2D PCs are important from the viewpoint of both academic and application uses. As already described in Chap. 1, there are many cases where a 2D PC suffices for observing novel phenomena. The term 2D PC is usually distinguished from a 2D PC slab, which is quasi-three-dimensional in a sense. Namely, for the former, the dimension (size) h in the direction perpendicular to the propagation direction is such that h ≫ a or λ (λ is the wavelength of light), so that an analysis based on plane waves is justified, while the reverse is true for the latter, that is, for the former, the eigenmodes with k parallel to the 2D plane are expressed as a combination of a set of plane waves. 2D PCs are classified into two types; one is of air cylinder type, and the other, of dielectric pillar type. We describe here three examples of 2D PCs that have mainly been fabricated and studied in Japan, together with the fabrication method.