Abstract
We present the design, fabrication and characterization of high quality factor silicon nitride nanobeam PhC cavities at visible wavelengths for coupling to diamond color centers in a cavity QED system. We demonstrate devices with a quality factor of similar to 24, 000 (+/- 250) around the zero-phonon line of the germanium-vacancy center in diamond. We also present an efficient fiber-to-waveguide coupling platform for suspended nanophotonics. By gently changing the corresponding effective indices at the fiber-waveguide interface, we achieve a coupling efficiency of similar to 96% (+/- 2%) at the cavity resonance. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement