Acousto-optical modulators usually rely on coherent diffraction of light by a moving acoustic wave, leading to bulky devices with a long interaction length. We propose a subwavelength acousto-optical structure that instead relies on a double resonance to achieve strong modulation at near-infrared wavelengths. A periodic array of metal ridges on a piezoelectric substrate defines cavities that create a resonant dip in the optical transmission spectrum. The ridges simultaneously support large flexural vibrations when resonantly excited by a radio-frequency signal, effectively deforming the cavities and leading to strongly nonlinear acousto-optical modulation. The nano-optical structure could find applications in highly compact photonic devices.

In this paper, we present a numerical study of the coupling between a nano-cavity, namely a Photonic Crystal Cavity (PCC) and a Nano-Particle (NP) in view of controlling the light extraction from the PCC. The main idea is to model such a near-field coupling for a NP designed to exhibit an electric dipole. We demonstrate the coupling to be very different allowing to manipulate the radiation spectrum of the whole structure in the far-field as a function of the NP position. The resonance wavelength of the PCC will be shifted toward the red region of the spectrum (up to 2 nm) while its quality factor changes dramatically according to the NP properties. This study opens the way to the development of a new kind of sources with both controllable wavelength resonance and radiation pattern.