Fabrication of triangular nanobeam waveguide networks in bulk diamond using single-crystal silicon hard masks

A scalable approach for integrated photonic networks in single-crystal diamond using triangular etching of bulk samples is presented. We describe designs of high quality factor (Q = 2.51 × 106) photonic crystal cavities with low mode volume (Vm = 1.062 × (λ/n)3), which are connected via waveguides supported by suspension structures with predicted transmission loss of only 0.05 dB. We demonstrate the fabrication of these structures using transferred single-crystal silicon hard masks and angular dry etching, yielding photonic crystal cavities in the visible spectrum with measured quality factors in excess of Q = 3 × 103.