Metallic photonic crystals at optical frequencies

The most important features of photonic crystals consisting of parallel metallic wires at optical frequencies are analyzed using a reliable and accurate numerical method. For a better understanding of the fundamental effects, the scattering of electromagnetic waves at metallic wires both in the radio frequency and in the optical frequency range are outlined first. This preparatory study includes plasmon resonances of a single wire and of a set of 9 wires. It is demonstrated that plasmon resonances cause flat band structures with many modes rather than photonic band gaps. At radio frequencies, the existence of a fundamental band gap for Ez waves is highly attractive for practical applications. We demonstrate that a fundamental band gap also exists at optical frequencies (under certain conditions) although metals lose their conductivity almost entirely and must be described by a complex permittivity.