Enhanced stability from co-resonant cavities in a monolithic array

TL;DR

This paper reports the fabrication and characterization of a monolithic array of micro-Fabry-Pérot cavities with high finesse, demonstrating reduced common-mode drift and potential applications in chip-scale quantum networks and laser stabilization.

Contribution

It introduces a novel fabrication method for monolithic cavity arrays with high finesse and demonstrates their stability and potential for quantum and laser applications.

Findings

Achieved cavity finesse of approximately 4750 with simple array design.

Correlated cavity frequency with etched depth, enabling predictable tuning.

Observed fivefold reduction in common-mode cavity drift across the array.

Abstract

We demonstrate a micro-Fabry-P\'erot cavity array through laser etching of high-surface-quality mirrors onto a single fused silica substrate. A cavity finesse of $4750\pm 200$ was achieved with a simple array design with $500~\mu m$ cavity length, $100~\mu m$ diameter micromirrors and $300~\mu m$ transverse separation. Arrays with up to 12 cavities were simultaneously tested for single mode operation, and absolute frequency measurements correlated strongly with the etched depth as measured by profilometry. Simultaneous measurements of the absolute resonant frequency for neighboring cavities showed a factor of 5 common-mode cavity drift reduction. Arrays of such cavities can be employed in chip-scale cavity QED networks (current cooperativity estimates are at the border of strong coupling for $^{87}$Rb atoms, $C=1$) as well as for precise laser stabilization at nearby wavelengths on a chip.