Phonon interaction with coupled photonic-plasmonic modes in a phoxonic cavity

We present a theoretical investigation of the acousto-optic interaction in a two-dimensional phoxonic crystal cavity containing a metallic nanowire. The crystal is constituted by a square array of cylindrical holes in a TiO2 matrix containing a cavity inside which a gold nanowire is introduced. The optical modes of the cavity are therefore of combined photonic-plasmonic character. We calculate the strength of coupling between these modes and the localized phonons of the cavity, based on the “Moving Interface” mechanism of acousto-optic coupling. We discuss the coupling strength as a function of the size and position of the metallic nanowire and compare the results with those of a cavity without metallic particle.