Hybrid photonic crystal cavity and waveguide for coupling to diamond NV-centers

TL;DR

This paper proposes a high-Q photonic crystal nanocavity design using a nanowire geometry on diamond to enhance light-matter interaction with NV centers, enabling efficient photon collection and coupling.

Contribution

It introduces a novel nanowire photonic crystal cavity structure with ultra-high Q and small mode volume for NV center integration in diamond.

Findings

Q factor exceeds 1.5 million

Mode volume is less than 0.52 (bb/b n_{GaP})^3

Efficient coupling and collection of NV emission possible

Abstract

A design for an ultra-high Q photonic crystal nanocavity engineered to interact with nitrogen-vacancy (NV) centers located near the surface of a single crystal diamond sample is presented. The structure is based upon a nanowire photonic crystal geometry, and consists of a patterned high refractive index membrane, such as gallium phosphide (GaP), supported by a diamond substrate. The nanocavity supports a mode with quality factor Q > 1.5 million and mode volume V < 0.52 (\lambda/n_\text{GaP})^3, and promises to allow Purcell enhanced collection of spontaneous emission from an NV located more than 50 nm below the diamond surface. The nanowire photonic crystal waveguide can be used to efficiently couple light into and out of the cavity, or as an efficient broadband collector of NV phonon sideband emission. The proposed structures can be fabricated using existing materials and processing techniques.