Optical orientation and probe-field spectroscopy of metastable atoms

A. V. Bezverbnyĭ, Vladimir S. Smirnov, Anatolii M Tumaikin

I. A. Kartashov, Sergei G Rautian, A. V. Shishaev

In the introduced paper the results of theoretical and experimental investigations in a branch of probe-field spectroscopy of degenerated metastable atoms in a laser radiation field of arbitrary intensity with taking into account of its anisotropical excitation and the presence of additional channels of radiant decay of upper level are presented. It is shown that for the degenerated levels which are excited anisotropically the absorption spectrum of the probe field contains, besides resonances caused by occupancy effects, resonances associated with the magnetic coherence and manifested in the form of peaks and dips with substantially different amplitudes and widths. A fundamentally new property of these resonances is that their widths are proportional to the intensity of the orienting field, and the amplitude of the narrowest resonance becomes appreciable when the orienting field is very strong.

Shengchi Liu, Pascal Neveu, J. Delpy +5 more

Abstract We perform spin noise spectroscopy experiments in metastable helium atoms at room temperature, with a probe light whose frequency is blue detuned from the D 0 line. Both circular birefringence fluctuations (Faraday noise) and linear birefringence fluctuations (ellipticity noise) are explored theoretically and experimentally. In particular, it is shown that in both cases but for different optical detunings, two noise resonances are isolated at the Larmor frequency and at twice the Larmor frequency with a behavior, which strongly depends on the orientation of the probe field polarization. The simple structure of metastable helium allows us to probe, model and explain the changes in the behavior of these peaks in terms of circular and linear dichroisms and birefringences as well as in terms of spin oscillation modes.

Matthias Raunhardt

Gerhard R. Guthöhrlein, Matthias Keller, Wulfhard K. Lange +1 more

Bertram Parister