Design and fabrication of ridge waveguide-based nanobeam cavities for on-chip single-photon sources

TL;DR

This paper presents a novel ridge waveguide nanobeam cavity design for efficient, broadband on-chip single-photon sources using quantum dots, with fabrication and optical characterization confirming cavity-enhanced emission.

Contribution

It introduces a new cavity design that improves emitter-mode coupling efficiency and broadband operation in low-refractive-index platforms, with experimental validation.

Findings

Achieved 0.73 outcoupling efficiency to the waveguide

Demonstrated cavity-enhanced spontaneous emission from quantum dots

Operates over a 9 nm bandwidth

Abstract

We report on the design of nanohole/nanobeam cavities in ridge waveguides for on-chip, quantum-dot-based single-photon generation. Our design overcomes limitations of a low-refractive-index-contrast material platform in terms of emitter-mode coupling efficiency and yields an outcoupling efficiency of 0.73 to the output ridge waveguide. Importantly, this high coupling efficiency is combined with broadband operation of 9 nm full-width half-maximum. We provide an explicit design procedure for identifying the optimum geometrical parameters according to the developed design. Besides, we fabricate and optically characterize a proof-of-concept waveguide structure. The results of the microphotoluminescence measurements provide evidence for cavity-enhanced spontaneous emission from the quantum dot, thus supporting the potential of our design for on-chip single-photon sources applications.