Signatures of the Mode Symmetries in Sapphire PhoXonic Cavities

1. Introduction

The study of wave propagation in general, and in periodic media in particular, has aroused great interest in the scientific community for several decades. In order for an extension of the notion of band gaps to electromagnetic waves to emerge, it was not until 1987 that photonic crystals were born.

Photonic band gap materials or photonic crystals (Joannopoulos et al., 2008; Yablonovitch, 1993) are periodic dielectric structures which have the ability to inhibit the propagation of light in certain directions, for a given frequency range.

In the image of photonic crystals, a composite material whose density and elastic constants are periodic functions of the position, may present, under certain conditions, bands prohibited for acoustic or elastic waves. These are materials with phononic band gaps called phononic crystals (Kushwaha et al., 1993; Pennec, Vasseur, Djafari-Rouhani et al, 2010).

To meet the growing needs to increase the performance of existing components or to propose new components, a new type of periodic structure combining the principle of photonic and phononic crystals which has been named phoXonic crystal (Eichenfield et al., 2009; Maldovan & Thomas, 2006a; Maldovan & Thomas, 2006b; Pennec, Djafari Rouhani, El Boudouti et al, 2010; Pennec et al., 2011; Rolland et al., 2012) was born. It was then expected an improved efficiency with regard to the strong confinement potentially achievable in these structures which present simultaneous photonic and phononic band gaps.