Optimized detection modality for double resonance alignment based optical magnetometer

In this work, we present a comprehensive and comparative analysis of two detection modalities, i.e., polarization rotation and absorption measurement of light, for a double resonance alignment based optical magnetometer (DRAM). We derive algebraic expressions for magnetometry signals based on multipole moments description. Experiments are carried out using a room-temperature paraffin-coated Caesium vapour cell and measuring either the polarization rotation or absorption of the transmitted laser light. A detailed experimental analysis of the resonance spectra is performed to validate the theoretical findings for various input parameters. The results signify the use of a single isotropic relaxation rate thus simplifying the data analysis for optimization of the DRAM. The sensitivity measurements are performed and reveal that the polarization rotation detection mode yields larger signals and better sensitivity than absorption measurement of light.