Ultralow dissipation optomechanical resonators on a chip

This work shows independent control over both optical and mechanical degrees of freedom in the microscale optomechanical resonator. Studying the dissipation of different mechanical modes of silica microtoroids it was possible to directly observe mechanical normal mode splitting between different modes of a micromechanical system. The fundamental radial breathing mode (RBM) can couple to flexural modes giving rise to avoided crossings. For the RBM this hybridization with low-Q flexural modes entails enhanced losses due to excitation of acoustic waves at the clamping region. This loss can be accurately modelled using finite element simulation which has then been employed to devise novel resonators with unprecedentedly low mechanical losses as described below.