Scanning cavity microscopy of a single-crystal diamond membrane

TL;DR

This study uses scanning cavity microscopy to analyze a fiber Fabry-Pérot microcavity with integrated diamond membranes, revealing how surface properties affect cavity performance and implications for quantum spin-photon interfaces.

Contribution

It provides detailed spatially resolved insights into how diamond surface and thickness influence cavity mode structure and finesse, guiding optimization of quantum interfaces.

Findings

Cavity finesse and mode structure depend on diamond thickness and surface topography.

Significant transverse-mode mixing occurs under diamond-like conditions.

Mode-character-dependent polarization splitting observed.

Abstract

Spin-bearing color centers in the solid state are promising candidates for the realization of quantum networks and distributed quantum computing. A remaining key challenge is their efficient and reliable interfacing to photons. Incorporating minimally processed membranes into open-access microcavities represents a promising route for Purcellenhanced spin-photon interfaces: it enables significant emission enhancement and efficient photon collection, minimizes deteriorating influence on the quantum emitter, and allows for full spatial and spectral tunability, key for controllably addressing suitable emitters with desired optical and spin properties. Here, we study the properties of a high-finesse fiber Fabry-P\'erot microcavity with integrated single-crystal diamond membranes by scanning cavity microscopy. We observe spatially resolved the effects of the diamond-air interface on the cavity mode structure: a strong correlation of the cavity finesse and mode structure with the diamond thickness and surface topography, significant transverse-mode mixing under diamond-like conditions, and mode-character-dependent polarization-mode splitting. Our results reveal the influence of the diamond surface on the achievable Purcell enhancement, which helps to clarify the route towards optimized spin-photon interfaces.