Planar-Waveguide External Cavity Laser Stabilization for an Optical Link with 1E-19 Frequency Stability

TL;DR

This paper demonstrates that a stabilized planar-waveguide external cavity laser can achieve ultra-high frequency stability comparable to fiber lasers, enabling cost-effective and robust optical links with 1E-19 stability over 100 km.

Contribution

The study shows that planar-waveguide external cavity lasers can be stabilized to achieve ultra-high frequency stability, comparable to fiber lasers, for optical links.

Findings

Achieved 1E-14 residual frequency stability of the ECL.

Established a 100 km optical link reaching 1E-19 relative stability.

ECL performance is comparable to fiber lasers in optical links.

Abstract

We stabilized the frequency of a compact planar-waveguide external cavity laser (ECL) on a Fabry-P\'erot cavity (FPC) through a Pound-Drever-Hall scheme. The residual frequency stability of the ECL is 1E-14, comparable to the stability achievable with a fiber laser (FL) locked to a FPC through the same scheme. We set up an optical link of 100 km, based on fiber spools, that reaches 1E-19 relative stability, and we show that its performances using the ECL or FL are comparable. Thus ECLs could serve as an excellent replacement for FLs in optical links where cost-effectiveness and robustness are important considerations.