Multichannel filtering properties of photonic crystals consisting of single-negative materials

The multichannel filtering properties have been investigated by means of the transfer-matrix method in the one-dimensional periodic structures containing two kinds of single-negative materials. Two sets of comb-like filtering channels appear simultaneously on the two sides of the bandgap with zero-effective phase. One is omnidirectional in the low frequency, and the other is angle-sensitive in the high frequency. The multichannel filtering properties of the structures, such as the channel number, the central frequencies and quality factors, may be modified by adjusting the period number and the layer thicknesses. It thus provides a simple way to design multichannel filter with specific channels.