Signatures of the Mode Symmetries in Sapphire PhoXonic Cavities

Abstract

The acousto-optic couplings mechanisms are investigated theoretically in photonic and phononic crystals with simultaneous band gaps. The authors have focused on the acousto-optic couplings inside a phoXonic cavity by taking into account two coupling mechanisms, the photo elastic effect and effect of movement of the interfaces. They discuss the symmetry of modes to distinguish those that don't interfere in an efficient way. They calculate the modulation of the frequency of the photonic mode during a period of acoustic oscillations with a finite element method (FE) (COMSOL®Multiphysics). The two mechanisms presented in the numerical calculations produce additive or subtractive effects in total acousto-optical coupling while depending on whether they are in phase or out of phase.