Silicon nitride membrane photonics

We propose a concept for realizing large area nanophotonic circuits in a silicon nitride membrane. Light is coupled into the membrane using a novel metallic photonic crystal grating coupler. A coupling loss of 5.5dB is predicted for TE polarized light at 1550nm. Waveguiding at telecoms wavelengths is achieved by using low loss photonic crystal defect waveguides. The propagation losses of the photonic crystal waveguides are estimated at 8.6dBmm^-1, comparable to early silicon photonic crystal waveguides. Using the proposed approach, photonic circuits can be fabricated using a single lithography and etching step. Thus the design scheme shows a route to low-cost fabrication.