Visible three-dimensional metallic photonic crystal with non-localized propagating modes beyond waveguide cutoff

Abstract

We report experimental realization of a 5-layer three-dimensional (3D) metallic photonic crystal structure that exhibits characteristics of a 3D complete bandgap extending from near-infrared down to visible wavelength at around 650 nm. The structure also exhibits a new kind of non-localized passband mode in the infrared far beyond its metallic waveguide cutoff. This new passband mode is drastically different from the well-known defect mode due to point or line defects. Three-dimensional finite-difference-time-domain simulations were carried out and the results suggest that the passband modes are due to intra-structure resonances.