Characterization of photonic bands in metal photonic crystal slabs

By rotating metal photonic crystal (PC) slab around ΓK and ΓM lattice directions, transmission spectra were measured to study photonic bands in such metal PC with a triangular lattice. We found that the photonic band diagram for the ΓM lattice direction is different from that for the ΓK direction. Approximate formulas of angular-dependent resonant frequencies are derived to quantitatively analysis the dispersion of metal PC. Furthermore, experimental results for the dominant resonances of (−1, 0) (ΓM) and (0,-1) (ΓK) confirm the accurate of formulas. All these results can be used to analyze and design devices based on metal PC.