High Q optomechanical resonators in silicon nitride nanophotonic circuits

We demonstrate integrated photonic circuits made from stoichiometric silicon nitride for effective integration of high Q micromechanical resonators and nano-optical components. Using silicon bulk micromachining techniques we fabricate free-standing highly tensile nanostrings exceeding 400 μm in length. The nanostrings are actuated using gradient optical force and their mechanical motion is readout with a sensitive interferometric scheme. A mechanical Q of 340 000 is obtained in vacuum. This fully integrated optomechanical circuit presents a promising scheme for on-chip high Q mechanical sensing applications.