Experimental and theoretical results for a two‐dimensional metal photonic band‐gap cavity

We demonstrate, by both microwave experiments and numerical simulation, that a two‐dimensional lattice of metal cylinders can form a complete photonic band‐gap (PBG) structure. The band structure exhibits a single broad PBG extending from zero frequency to a threshold frequency, above which all modes may propagate in some direction. A single cylinder removed from the lattice produces a defect mode localized about the defect site, with an energy density attenuation rate of 30 dB per lattice constant. The frequency dependence of the transmission through a finite thickness of this structure is also calculated in good agreement with the measurements. We suggest that the defect mode resonant cavity when formed by appropriate low loss metals may be advantageous for use in PBG high energy accelerator structures that we are evaluating.