Extraordinary optical transmission through multiple corrugated metallic layers

The enhancement of light transmittance through multiple corrugated grating with double metallic layers is investigated theoretically. Our calculation of transmittance-reflectance through multiple corrugated grating is performed using the coordinate translation method, which is widely used for the calculation of various gratings. For the multiple corrugated grating with double metallic layers, it is confirmed for the first time that the physical mechanism of optical enhancement can be attributed to excitation of wave-guided modes inside the dielectric gap when an F-P like dielectric cavity is formed between two adjacent metal layers.