LAUSR

Abstract We demonstrate a fork-shape edge coupler consisting of a two-tip taper and subwavelength gratings for optical interconnects in optical communication scenarios. The proposed fiber-to-chip edge coupler can achieve a low coupling loss of around 1.0 dB at 1550 nm wavelength for TE mode. The edge coupler also presents a stable performance over a 100-nm wavelength range, owing to the high degree of freedom of subwavelength gratings. The effects of fabrication deviations and fiber misalignments on the coupler are investigated and analyzed in detail. Three types of potential deviations during the fabrication process are taken into consideration, including the distance deviation between coupler facet and the chip facet, lithography deviations, and surface roughness of the chip facet. As for the discussions about the effects of fiber misalignments, both the spatial displacement and the angular misalignment of the optical fiber are included. Simulation results indicate that the fabrication deviations can have certain impacts on the coupling performances and the edge coupler is tolerant to the fiber misalignments. Our numerical simulations and theoretical analysis can provide useful guidance for the fabrication processes and experimental measurements of the proposed edge coupler.