Low-drift Zeeman shifted atomic frequency reference

TL;DR

This paper introduces ZSAR, a low-drift atomic frequency reference using the Zeeman effect, achieving tens of GHz tuning range with high stability, suitable for laser stabilization and adaptable to various atomic species.

Contribution

The paper presents a novel Zeeman-based frequency reference method with a large tuning range and demonstrated stability, using a heated rubidium vapor cell and permanent magnets.

Findings

Tens of GHz tuning range achieved.

2.5 MHz RMS stability over 24 hours.

Method adaptable to other atomic species.

Abstract

We present a simple method for producing a low-drift atomic frequency reference based upon the Zeeman effect. Our Zeeman Shifted Atomic Reference `ZSAR' is demonstrated to have tens of GHz tuning range, limited only by the strength of the applied field. ZSAR uses Doppler-free laser spectroscopy in a thermal vapor where the vapor is situated in a large, static and controllable magnetic field. We use a heated $^{85}$Rb vapor cell between a pair of position-adjustable permanent magnets capable of applying magnetic fields up to 1 T. To demonstrate the frequency reference we use a spectral feature from the Zeeman shifted D1 line in $^{85}$Rb at 795 nm to stabilize a laser to the 7S$_{1/2}$ $\longrightarrow$ 23P$_{1/2}$ transition in atomic cesium, which is detuned by approximately 19 GHz from the unperturbed Rb transition. We place an upper bound on the stability of the technique by measuring a 2.5 MHz RMS frequency difference between the two spectral features over a 24 hour period. This versatile method could be adapted easily for use with other atomic species and the tuning range readily increased by applying larger magnetic fields.