Spectral engineering of coupled open-access microcavities

TL;DR

This paper demonstrates the spectral and spatial engineering of coupled open-access microcavities with tunable coupling, enabling control over mode splitting and properties for advanced photonic applications.

Contribution

It introduces a method to engineer coupling in microcavities using Focused Ion Beam milling, with detailed experimental and theoretical analysis of spectral, spatial, and polarization properties.

Findings

Normal mode splittings up to 20 meV observed

Mode volumes around 10 times lambda cubed achieved

Transition from isolated to coupled cavities characterized

Abstract

Open-access microcavities are emerging as a new approach to confine and engineer light at mode volumes down to the $\lambda^3$ regime. They offer direct access to a highly confined electromagnetic field while maintaining tunability of the system and flexibility for coupling to a range of matter systems. This article presents a study of coupled cavities, for which the substrates are produced using Focused Ion Beam milling. Based on experimental and theoretical investigation the engineering of the coupling between two microcavities with radius of curvature of \SI{6}{\micro\meter} is demonstrated. Details are provided by studying the evolution of spectral, spatial and polarisation properties through the transition from isolated to coupled cavities. Normal mode splittings up to 20 meV are observed for total mode volumes around $10 \times \lambda^3$. This work is of importance for future development of lab-on-a-chip sensors and photonic open-access devices ranging from polariton systems to quantum simulators.