Effect of preliminary two-frequency optical pumping on resonance fluorescence of sodium atomic beams

I. V. Zhurkin, L. Yu. Khryashchev

Ning Ding, Guoguo Kang, Xiaoxu Zhang +7 more

The magneto-optical resonance response of sodium atoms generated by a high-energy solid-state pulse Nd:YAG laser is studied in different external magnetic fields. We investigate the resonance fluorescence signal of sodium atoms in a simulated sea fog environment based on the laser-induced plasma (LIP) effect. By ionizing an NaCl solution spray to generate sodium atoms in an atmospheric environment, we build a Bell–Bloom magneto-optical resonance system under laboratory conditions. With the help of laser-induced breakdown spectroscopy (LIBS) and extinction spectrum, we obtain sodium atoms with a lifetime of 250 µs. A narrowband tunable continuous wave (CW) 589-nm laser tuned at the D 2 line with a modulation frequency around the Larmor frequency is used as the pump beam to polarize sodium atoms in the test magnetic field. We find that the magneto-optical resonance signals vary with different external magnetic fields and the positions of the resonance signal are consistent with the theoretical values. An intrinsic magnetometric sensitivity of 620.4 pT in a 1-Hz bandwidth is achieved.

I. V. Zhurkin, L. Yu. Khryaschev

P. Thomann

The fluorescent intensity of two-level atoms irradiated by a near-resonant amplitude-modulated light wave is calculated in the Bloch model. The analogy with magnetic resonance in a strong oscillating field making an arbitrary angle with the static field is pointed out. Experimental evidence of the predicted parametric and multiple quantum resonances has been obtained with an atomic beam of sodium. Optical pumping was used to prepare the sodium atoms as two-level systems.

Barry L. Sharp, A. Goldwasser

Renu Tripathi, Kevin Heesh, Christiane Ebongue +4 more

Measurement and monitoring of geomagnetic field in the mesosphere has many potential applications such as detection of oceanic currents, mapping of large-scale magnetic structures, and study of electric-current fluctuations in the ionosphere. Remote measurement of the geomagnetic field can be performed by optical pumping of sodium atoms in the mesosphere with an amplitude modulated (AM) light at the Larmor precession frequency, and observing the magnetic resonance in fluorescence at a ground station. In this context, we have conducted an experiment in the laboratory to demonstrate remote magnetic field measurement using fluorescence signal from a sodium cell. Sodium atoms in the cell are interrogated with AM light produced by an acousto-optic modulator (AOM), introduced in the beam path of a frequency-doubled amplified sodium laser made in our laboratory. Magnetic resonance observed in sodium cell fluorescence is studied as a function of varying magnetic field intensity. Characteristics of the magnetic resonance such as linewidth and contrast (or SNR), and their dependence on optical power density, AM duty cycle, B-field orientation and intensity are studied. Theoretical modeling and experimental measurements are also carried out to determine the sensitivity of the magnetometer for realizing remote magnetometry with mesospheric sodium atoms.