  Q-enhanced racetrack micro-resonators for the silicon nitride photonics
integration platform have been designed, fabricated and characterized. The
proposed geometries permit to mitigate the impact of radiation loss at curved
waveguides, one of the major limitations of silicon nitride circuits, therefore
providing an increase of the intrinsic Q factor of micro-resonators when
compared with the conventional structures with the same bent radii. The schemes
put forward in this work permit a reduction of the size of the devices that has
a direct impact on the integration scale in this platform. When used in the
curved sections of waveguides routing optical signals within an integrated
photonic circuit, these geometries provide a reduction of the radiation loss
and permit the use of smaller bent radii and to increase the circuit
integration density.
