Simulation on fiber-to-waveguide coupling efficiency of Si3N4 grating coupler for quantum nano-photonics

Abstract

Recently, Si3N4 has been investigated as a quantum nano-photonics platform due to its low propagation loss and high refractive index. Light can be efficiently coupled from fiber to Si3N4 waveguide and vice versa using a grating coupler. We perform computational simulations on grating couplers to find the optimum geometric conditions of fiber-to-waveguide coupling efficiency in the telecom wavelength range. According to our simulation, the fiber-to-waveguide coupling efficiency can be more than 60%. Our results would be useful for future quantum optics experiments.