Triangular cross-section grating couplers for integrated quantum nanophotonic hardware in silicon carbide

TL;DR

This paper presents the design, fabrication, and characterization of fishbone grating couplers in silicon carbide, achieving up to 24% efficiency in extracting light from quantum nanophotonic devices for integrated quantum applications.

Contribution

It introduces a scalable method for efficient light outcoupling from silicon carbide quantum nanophotonic devices using optimized fishbone grating couplers.

Findings

Achieved up to 24% efficiency in light outcoupling.

Designed grating couplers compatible with color center integration.

Demonstrated effective operation at cryogenic temperatures.

Abstract

We design, fabricate, and characterize fishbone grating couplers for triangular cross-section photonics in silicon carbide compatible with color center integration. The periodic and aperiodic grating coupler designs are optimized to outcouple up to 31% of light in the fundamental TE mode of a triangular waveguide. The devices are fabricated using an ion beam etching process in a 4H-SiC sample implanted with NV center ensembles. The room-temperature transmission and the cryogenic NV center photoluminescence collection measurements indicate experimental grating coupler efficiency of up to 24%. This result provides a scalable method to efficiently extract color center light from SiC quantum nanophotonic devices to free-space optics.