A 1D phoxonic crystal

Simultaneous confinement of light and sound in the same cavity generates a strong phonon-photon interaction, known as optomechanical (OM) coupling. Several optomechanical systems provided already proof of concept demonstrations for enhanced telecommunication devices and sensors. And using OM cavities, the basis for coherent phonon manipulation have already been set and/or propose. OM crystals (cavities built using the concepts of photonic and phononic crystals) target high frequency phonons. High frequency phonons have a competitive advantage as the thermal phonon population decreases with frequency. Using OM crystals, a recent work achieved a single confined phonon by OM cooling starting at moderate cryogenic temperatures. If the OM cavity is built using a complete phonon bandgap we calculated a better limitation of phonon losses, robust to fabrication imprefections. Cavities with simultaneous bandgap for light and sound are known as phoXonic crystals. We study the OM interaction in a 1D phoXonic crystal cavity. The cavity consists of a suspended silicon nanobeam made with the repetition of a cell with a centered hole and a centered stub. A defect made by changing appropriately the cell dimensions towards the nanobeam center confines simultaneously light and sound. We present the experimental characterization of such structure, where we have detected by OM transduction modes inside the complete bandgap.