Effects of Organic Thin Films on Local Resonance of Metamaterials under Photoexcitation

Abstract

We demonstrate that the local resonance of metamaterials can be tuned by the effects of organic thin filmsunder photoexcitation. Tris (8-hydroxyquinolinato) aluminum (Alq3) layers are deposited on metamaterial/silicon hybrid structures. By varying the thickness of the Alq3 layer on the subwavelength scale, theresonant peak of the metamaterial becomes very adjustable, due to the effect of a thin dielectric substrate. In addition, under photoexcitation all the spectral peaks of the resonance shift to higher frequencies. Thisoriginates from the reduction of the capacitive response generated inside the gaps of split-ring resonators. The adjustability of the electromagnetic spectrum may be useful for developing optical systems requiringrefractive-index engineering and active optical devices.