Optical transmission of corrugated metal films on a two-dimensional hetero-colloidal crystal.

The near infrared transmission of corrugated metal films deposited on hetero-colloidal crystals is investigated. The transmission response of the quasi-three-dimensional (quasi-3D) metal film is modified by controlling the nominal thickness of a dielectric layer pre-deposited on the top surface of the colloidal crystal to form a new hetero-colloidal crystal. An extraordinary optical transmission (EOT) phenomenon could be presented in such metallodielectric (MD) architectures. We have found that the main transmission peak is suppressed as the thickness of the intercalated dielectric layer is increased. We propose that the observed EOT is a result of constructive interference between a localized sphere-like plasmon mode and an index-guided eigen mode mainly confined in the colloidal crystal, which is confirmed by our numerical simulations. Based on the MD microstructures, a distinct plasmon sensitivity response difference is achieved, which indicates potential applications for biochemical sensing.