Theory of double resonance magnetometers based on atomic alignment

Abstract

We present a theoretical study of the spectra produced by optical/radio-frequency double resonance devices, in which resonant linearly polarized light is used in the optical pumping and detection processes. We extend previous work by presenting algebraic results which are valid for atomic states with arbitrary angular momenta, arbitrary rf intensities, and arbitrary geometries. The only restriction made is the assumption of low light intensity. The results are discussed in view of their use in optical magnetometers.

Experimental study of laser-detected magnetic resonance based on atomic alignment

“…We show that the experimental spectra obtained for cesium are in excellent agreement with the theoretical model presented in [1] and we investigate the limitations of this model. In contrast to prior work reported in [5,6,9] we detect the signal at both the first and second-harmonic of the applied rf field.…”

“…In practice, the three steps occur simultaneously and the approach is valid only if steady state conditions are reached for the first two steps. As explained in [1], the approach is thus valid only if the optical pumping rate is negligible compared to the relaxation rates, i.e., for low light powers. The model calculates the evolution of the alignment multipole moments m 2,q via a density matrix approach, where the moments m 2,q are defined with respect to a quantization axis aligned with B 0 and relax with rates Γ |q| .…”

“…quency ω. Lock-in detection is used to record spectra of the first and second harmonic signals and the results are compared with the theoretical predictions of [1]. We investigated the effects of the experimental parameters on the spectral line shapes of the in-phase and quadrature components of both signals.…”

“…The double resonance alignment magnetometer model (DRAM model) developed in [1] provides algebraic expressions for the expected resonance signals. In that model, the line shapes are calculated following a threestep approach: creation of alignment by optical pumping, magnetic resonance, and detection of the oscillating steady state alignment.…”

“…In a recent publication [1], our group presented a theoretical study of the spectra produced by optical/radiofrequency double resonance devices in which resonant linearly polarized light is used in the optical pumping process. That study led to very general algebraic results, valid for atomic states with arbitrary angular momenta, for arbitrary rf intensities, and for arbitrary geometries, valid however only for low laser light power.…”