Optical metasurfaces for subwavelength difference operations

Abstract

Coupled metal nanostructures supporting localized surface plasmon resonances are represented as a nanoscale optical circuit that takes light fields as inputs and forms linear combinations of them with complex coefficients. The subwavelength arrays of these circuits form a metasurface that performs mathematical operations in two dimension on an incident light field. We demonstrate this concept with subwavelength scale plasmonic circuits that perform difference operations. The metasurface is fabricated from the arrays of coupled gold nanorods where each group of three rods forms the difference circuit. The operation of the metasurface is demonstrated experimentally.