Optimized optomechanical crystal cavity with acoustic radiation shield

We present the design of an optomechanical crystal nanobeam cavity that combines finite-element simulation with numerical optimization, and considers the optomechanical coupling arising from both moving dielectric boundaries and the photo-elastic effect. Applying this methodology results in a nanobeam with an experimentally realized intrinsic optical Q-factor of $1.2×106$⁠, a mechanical frequency of 5.1 GHz, a mechanical Q-factor of $6.8×105$ (at T = 10 K), and a zero-point-motion optomechanical coupling rate of g = 1.1 MHz.