Laser intracavity absorption magnetometry for optical quantum sensing

TL;DR

This paper introduces laser intracavity absorption magnetometry (LICAM), a novel optical quantum sensing technique that significantly enhances magnetic sensitivity using diode lasers and intracavity absorption, promising ultra-sensitive measurements under ambient conditions.

Contribution

The paper presents LICAM, extending intracavity absorption spectroscopy to magnetometry with NV centers, achieving substantial sensitivity improvements and a practical self-sustaining laser setup.

Findings

475-fold enhancement in optical contrast near lasing threshold

180-fold improvement in magnetic sensitivity over single-pass methods

Projected shot-noise-limited sensitivity reaching the fT/Hz^{1/2} scale

Abstract

Intracavity absorption spectroscopy (ICAS) is a well-established technique for detecting weak absorption signals with ultrahigh sensitivity. Here, we extend this concept to magnetometry using nitrogen-vacancy (NV) centers in diamond. We introduce laser intracavity absorption magnetometry (LICAM), a concept that is in principle applicable to a broader class of optical quantum sensors, including optically pumped magnetometers. Using an electrically driven, edge-emitting diode laser that operates self-sustainably, we show that LICAM enables highly sensitive magnetometers operating under ambient conditions. Near the lasing threshold, we achieve a 475-fold enhancement in optical contrast and a 180-fold improvement in magnetic sensitivity compared with a conventional single-pass geometry. The experimental results are accurately described by a rate-equation model for single-mode diode lasers. From our measurements, we determine a projected shot-noise-limited sensitivity in the $\mathrm{pT}\,\mathrm{Hz}^{-1/2}$ range and show that, with realistic device improvements, sensitivities down to the $\mathrm{fT}\,\mathrm{Hz}^{-1/2}$ scale are attainable.