Low-pass Spatial Filtering Using Optically Thinner Left-handed Photonic Crystals

Different form previous two-dimensional coated photonic crystals, in this paper we investigate an optically thinner one that is made of dielectric tubes arranged in a close-packet square lattice. Without the metallic cores, this structure is low-loss and convenient to fabricate. A low-pass spatial filter made from the photonic crystal is demonstrated by dispersion analysis and numerical simulations. The high-spatial-frequency components, whose incident angles exceed the critical value, are reflected totally. However, the low-spatial-frequency components are coupled to the Bloch modes of the photonic crystal and permeate.