Ultra-stable lasers using hollow-core fibre

TL;DR

This paper demonstrates a novel hollow-core fibre-based laser stabilization method that achieves ultra-stable frequency performance comparable to traditional ultra-low expansion cavity systems, with improved simplicity and long-term stability.

Contribution

It introduces the first laser stabilized to a hollow-core fibre, offering a simpler, scalable alternative to ULE cavity-stabilized lasers with comparable stability.

Findings

Frequency instability of 4.6x10^-15 at 1 s

Frequency drift of 88 mHz/s, reducible to 3.7 mHz/s

Long-term stability confirmed over 3 years

Abstract

Ultra-stable lasers are fundamental to a growing range of applications, including optical frequency metrology, fundamental physics and quantum sensing. Their outstanding performance is achieved by stabilizing their frequency to Ultra-Low Expansion (ULE) optical cavities. However, the complexity of fabrication and assembly of these systems - even for compact designs - has been limiting their widespread deployment. While micro-resonators and optical fibre delay lines offer alternatives, their performance is significantly limited by thermally-induced frequency drift. Here we demonstrate, for the first time to the best of our knowledge, a laser stabilised to a Hollow Core Fibre (HCF) achieving comparable performance to ULE cavity-stabilised lasers. We achieve a frequency instability of 4.6x10-15 at 1 s and a frequency drift of 88 mHz/s, reducible to 3.7 mHz/s with thermal correction. Furthermore, over 3-year characterization confirms the HCF's predictable long-term behaviour. These results and the simplicity of the HCF-based system pave the way to a high-performance and scalable solution for ultra-stable laser sources.