Remote Atmospheric Optical Magnetometry

In this paper, an analysis of a remote atmospheric magnetometry concept is considered, using molecular oxygen as the paramagnetic species. The objective is to use this mechanism for the remote detection of underwater and underground objects. Kerr self-focusing is used to bring a polarized, high-intensity, laser pulse to focus at a remote detection site where the laser pulse induces a ringing in the oxygen magnetization current. This current creates a co-propagating electromagnetic field behind the laser pulse, i.e., the wakefield, which has a rotated polarization that depends on the background magnetic field. The detection signature for underwater and underground objects is the change in the wakefield polarization between different measurement locations. The coupled Maxwell-density matrix equations are used to describe the oxygen magnetization in the presence of an intense laser pulse and ambient magnetic field. The magnetic dipole transition line that is considered is the b¹Σ⁺_g−X³Σ⁻_g transition band of oxygen near 762 nm. The major challenges are the collisional dephasing of the atmospheric oxygen transitions and the strength of the effective magnetic dipole interaction.