Polarization measurement of Cs using the pump laser beam

TL;DR

This paper presents a novel method to measure Cs atom polarization directly via pump laser absorption, avoiding probe beam perturbation, validated in a SERF magnetometer with real-time capability.

Contribution

It introduces a new approach to determine atomic spin polarization from pump laser absorption, enhancing sensor accuracy and enabling silent, real-time measurements.

Findings

Method agrees with theoretical predictions

Operates in silent mode with real-time observation

Includes diffusion effects in magnetic response model

Abstract

In the optical pumping systems based on the pump-probe arrangement, the spin polarization of the atoms is generally monitored utilizing the probe laser beam, in which way an extra perturbation must be introduced and thus affects the normal operation of the sensors. By investigating the absorption rate of the circularly polarized pump laser, here we demonstrate the feasibility of extracting the electron-spin polarization from the transmitted pump laser intensity. We experimentally validate the method in a spin-exchange relaxation free (SERF) magnetometer and the results are in excellent agreement with the theory. The scheme operates in a silent mode and features a real-time observation. We also study the corresponding magnetic field response of the SERF magnetometer and a term arising from the diffusion effects has been added to the original model to explain the discrepancy of the response.