Diode laser noise-spectroscopy of low-frequency atomic fluctuations in rubidium vapor
Instituto de Física, Facultad de Ingeniería, Casilla de Correo 30, 11000 Montevideo, Uruguay
Corresponding author: a email@example.com
Revised: 3 September 2008
Published online: 14 November 2008
We have observed resonant features in the spectrum of the fluctuations of a linearly polarized diode laser beam transmitted through a rubidium vapor cell, corresponding to the evolution of the atomic spin in the presence of a constant magnetic field. The observed resonances occur at a noise frequency corresponding to twice the Larmor frequency of ground state rubidium atoms and are due to two-photon Raman processes involving the carrier frequency and the noise sideband. We observed noise resonances for frequencies of the order of one MHz via heterodyne detection. Due to nonlinear Faraday rotation, we detected emitted light with polarization orthogonal to the incident field. The influence of the laser light fluctuations on the transmitted light noise spectrum was investigated by using two diode laser sources with different spectral bandwidths. The observed features are in qualitative agreement with a semiclassical theoretical model that treats laser fluctuations up to first order.
PACS: 32.80.Qk – Coherent control of atomic interactions with photons / 42.50.Gy – Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008