Infrared transmission resonances in double-layered, complementary-structure metallic gratings.

A double-layered metallic grating (metal-dielectric-metal) with a complementary capacitive (isolated discs) / inductive (connected film with apertures) structure exhibits multiple infrared transmission resonances peaks with up to 70% at wavelength ranges corresponding to local modes for geometric dimensions less than a wavelength. The period, dielectric thickness, refractive index and unit cell size of the periodic structure modulate the local mode positions and amplitudes. The electromagnetic field distribution and energy flow in the structure explain the relation of transmission resonance, local modes, and distributed surface plasma wave modes.