Optical Enhanced Transmission of Double Layer Ultrathin Metallic Films

Double layer ultrathin metallic films composed of an aluminum film with thickness of 33 nm on copper films with thickness of 16 nm or 32 nm were deposited on polyester foil by cylindrical medium frequency magnetron sputtering in turn. Transmittance and reflectance of these films were measured and compared to each composite film, as well as absorptance, respectively. The results show that the reflectance increases, while both the transmittance and the absorptance decrease with the increase in copper film thickness. At the same time, the three optical parameters of the double layer film were calculated theoretically. Compared to theoretical results, there is an increase in transmittance, while a decrease in reflectance and absorptance for the double layer on experimental results. It is concluded that the optical properties of the double layer films are not simply the sum of the two composite films, there is an enhanced transmission effect to electromagnetic wave at the double layer metallic film.