High transmission of system "dielectric grating thin metal film - dielectric grating"

The analysis of transmission of system the dielectric grating-metal thin film-dielectric grating-substrate by the coupled wave method (CWM) is conducted. It is revealed that at certain parameters the system has the anomalous high transmittance and practically zero reflectance on defined wavelengths. For example, the silver film with thickness of 0.0385 mum placed between two gratings with certain parameters transmit more than 0.86 and 0.83 corresponding to TE and TM polarizations on wavelength of 1.5 mum. The silver film in vacuum with same thickness has the reflectance higher than 0.98 and transmittance less than 0.004. Transmission sharply drops at deviation of the wavelength from the defined value. The system the dielectric with high refraction coefficient-metallic thin film-dielectric with high refraction coefficient has the analogous spectrum characteristics