Extraordinary Transmission of Light Through Freestanding Au Films with Subwavelength Apertures and Double Slits

We demonstrated the extraordinary transmission of light through a freestanding Au thin film with a 7×7 subwavelength aperture array and double slits. Firstly, we observed the dependence of the change in the light transmission through a plasmonic structure on the pitch size of the aperture array. Also, we fabricated a freestanding Au thin film to avoid the effects of absorption and reflection of the substrate. We perforated the 7×7 subwavelength hole array on the Au film for extraordinary optical transmission caused by the electric field enhancement from the structures. Additionally, we designed a hybrid structure composed of 7×7 subwavelength apertures and double slits to enhance the transmission of the light. The normalized-to-area transmission of the hybrid structures was approximately five times greater than that of the structures without double slits.