Geometry dependence of field enhancement in 2D metallic photonic crystals.

Geometry dependence of surface plasmon resonance of 2D metallic photonic crystals (PCs) was assessed using rigorous 3D finite difference time domain analysis. PCs of noble metallic rectangular and cylindrical nanopillars in square and triangular lattices on thick noble metal film were simulated for maximum field enhancement. It was found that the period, size and thickness of the nanopillars can be tuned to excite of surface plasmons at desired wavelengths in visible and near-infrared ranges. Maximum electric field enhancement near the nanopillars was found to be greater than 10X. The detail analysis of PCs tuned for 750 nm wavelength showed that thickness of nanopillars was the most sensitive parameter for field enhancement, and triangular lattice PCs had the wider enhancement bandwidth than square lattice PCs. Results showed that these PCs are sensitive with incident angle (theta) but not with polarization angle (phi).