Effective plasma frequency in one-dimensional metallic-dielectric photonic crystals

Photonic band structures of one-dimensional (1D) metallic-dielectric photonic crystals (MDPCs) are studied theoretically. We show that a 1D MDPC can be considered as an effective metallic medium with a well-defined effective plasma frequency. This effective plasma frequency is found to be inversely proportional to the optical thickness of the dielectric layer and is independent of either the constituent metal or the thickness of the metallic layer. By increasing the optical thickness of the dielectric layer, the effective plasma frequency of a 1D MDPC can be depressed into extremely low frequencies such as far infrared or even below. (C) 2005 American Institute of Physics.