Ultra-high-Q nanobeam cavity design in Diamond

TL;DR

This paper introduces a novel diamond nanobeam cavity design with a triangular cross-section, achieving ultra-high quality factors and low mode volume, which enhances optical properties and simplifies fabrication processes.

Contribution

A new nanobeam cavity design in diamond with a triangular cross-section that achieves ultra-high-Q factors and does not require a free-standing membrane.

Findings

Achieved predicted Q factor of approximately 2.51 million.

Mode volume measured at 1.06 times (λ/n)^3.

Mode radiation is predominantly upward.

Abstract

A novel nanobeam design with a triangular cross-section is proposed. This design makes possible implementing nanocavities with improved optical properties. The dependence of a diamond-based cavity quality factor Q and mode volume Vm on geometry parameter space are studied via 3D FDTD computations. An ultra-high-Q cavity with Q\aprox 2.51 \times 10^6 and Vm=1.06 \times ({\lambda}/n)^3 is predicted. The mode preferential radiation is upward. The implications on the potential applications are discussed. The proposed nanobeam enables fabrication of the cavity without relying on a pre-existing free-standing diamond membrane as required in most previous approaches.