  We demonstrate integrated optomechanical circuits with high mechanical
quality factors prepared from nanocrystalline diamond thin films. Using
chemomechanical polishing, the RMS surface roughness of as grown
polycrystalline diamond films is reduced below 3nm to allow for the fabrication
of high-quality nanophotonic circuits. By integrating free-standing
nanomechanical resonators into integrated optical devices, efficient read-out
of the thermomechanical motion of diamond resonators is achieved with on-chip
Mach-Zehnder interferometers. Mechanical quality factors up to 28,800 are
measured for four-fold clamped optomechanical resonators coupled to the
evanescent near-field of nanophotonic waveguides. Our platform holds promise
for large-scale integration of optomechanical circuits for on-chip metrology
and sensing applications.
