High-contrast grating mirror embedded in acoustic shield for optomechanics

By enabling high reflectivity from a single layer of dielectric, high-contrast gratings (HCGs) provide an exciting platform for optomechanics. In the interest of enhancing the mechanical quality factor of such devices, we have combined photonic and phononic engineering to fabricate HCG mirrors within a structure containing phononic bandgaps. In this way, we realize optomechanical devices that simultaneously exhibit high reflectivity, ultralow mass, and ultrahigh mechanical quality factors. Our initial devices are designed to trade off optimal acoustic and optical performance. We have incorporated these devices into optical cavities, which we probe in order to determine their optical and mechanical properties.