Gap plasmon-based metasurfaces: fundamentals and applications

We present the exciting functionalities of gap surface plasmon-based metasurfaces for light manipulation in reflection due to the excitation of gap surface plasmon resonances allowing for efficient control of phase and amplitude of reflected light. We specifically demonstrate that such plasmonic metasurfaces can be utilized for efficient unidirectional polarization-controlled coupling of incident light to propagating surface plasmon polariton modes. Fabricated metasurfaces that operate at telecommunication wavelengths 1500-1600nm feature a maximum coupling efficiency of ~25% for either of two linear polarizations of incident light and surface plasmon directivity exceeding 100.