GaN directional couplers for integrated quantum photonics

TL;DR

This paper proposes large cross-section GaN waveguides for integrated quantum photonics, demonstrating high-quality fabrication, single-mode operation, and high-visibility two-photon interference in directional couplers.

Contribution

It introduces a novel GaN waveguide architecture for quantum photonics, including design, fabrication, and experimental validation of directional couplers.

Findings

High-quality facets observed via SEM

Single-mode operation at 800 nm confirmed

96% Hong-Ou-Mandel interference visibility

Abstract

Large cross-section GaN waveguides are proposed as a suitable architecture to achieve integrated quantum photonic circuits. Directional couplers with this geometry have been designed with aid of the beam propagation method and fabricated using inductively coupled plasma etching. Scanning electron microscopy inspection shows high quality facets for end coupling and a well defined gap between rib pairs in the coupling region. Optical characterization at 800 nm shows single-mode operation and coupling-length-dependent splitting ratios. Two photon interference of degenerate photon pairs has been observed in the directional coupler by measurement of the Hong-Ou-Mandel dip with 96% visibility.