Simple tunable phase-locked lasers for quantum technologies

TL;DR

This paper presents a simple, cost-effective method to generate tunable, phase-locked laser sources with sub-Hz linewidths suitable for quantum technology applications.

Contribution

It introduces a scalable, fiber-based approach to produce phase-locked lasers with tunable frequency differences up to 15 GHz using a single laser diode.

Findings

Achieved sub-Hz relative linewidth in phase-locked lasers.

Produced tunable difference frequencies up to approximately 15 GHz.

Demonstrated a simple, scalable architecture for quantum laser sources.

Abstract

In a wide range of quantum technology applications, ranging from atomic clocks to the creation of ultracold or quantum degenerate samples for atom interferometry, optimal laser sources are critical. In particular, two phase-locked laser sources with a precise difference frequency are needed for efficient coherent population trapping (CPT) clocks, gray molasses laser cooling, or driving Raman transitions. Here we show how a simple cost-effective laser diode can selectively amplify only one sideband of a fiber-electrooptically-modulated seed laser to produce moderate-power phase-locked light with sub-Hz relative linewidth and tunable difference frequencies up to $\approx 15\,$GHz. The architecture is readily scalable to multiple phase-locked lasers and could conceivably be used for future on-chip compact phase-locked laser systems for quantum technologies.