Standalone optical frequency-offset locking electronics for atomic physics

TL;DR

This paper introduces a standalone, modular electronic system for locking laser frequencies with high precision and large tuning range, demonstrated through cold atom spectroscopy, suitable for diverse atomic physics applications.

Contribution

The authors develop a cost-effective, high-performance laser locking system using off-the-shelf components, achieving large capture range, fast response, and high resolution without needing a dedicated clock reference.

Findings

Achieved a locking range greater than 1 GHz.

Demonstrated a frequency resolution of 1.9 kHz.

Attained a fractional frequency instability of 10^{-11}/√τ at 780 nm.

Abstract

We present a standalone frequency-offset locking system for controlling narrow-linewidth lasers using off-the-shelf electronic components. We lock two frequency-doubled 1560 nm lasers to a stable primary laser operating at 780 nm via their optical beat note. This radio-frequency beat note is fed through a broadband variable divider, a frequency-to-voltage converter, and a proportional-integrator controller to lock each follower laser to a tunable offset frequency relative to the primary. This architecture provides a large capture range ($> 1$ GHz), fast response times ($< 1$ ms), and high linearity. We achieve a frequency resolution of 1.9 kHz and a short-term fractional frequency instability $10^{-11}/\sqrt{\tau \rm (s)}$ at 780 nm without the need for a dedicated, precise clock reference. We perform high-resolution spectroscopy of cold $^{87}$Rb atoms to demonstrate the tunability and precision of our locking system. We designed the system to be modular and extensible, making it applicable to a wide variety of atomic physics experiments, including laser cooling, spectroscopy, and quantum sensing with atoms, ions, and molecules.