David J. Fulton

Electromagnetically induced transparency in N-level cascade schemes

Abstract We examine electromagnetically induced transparency (EIT) in cascade schemes with N levels and N −1 fields. We show that transparency effects are present when N is odd and that destruction of EIT is present on line centre when N is even. We predict multiple dark resonances in such schemes due to multiphoton EIT effects. By examining atomic rubidium we propose methods of achieving such schemes by use of coupling rf fields into hyperfine levels.

Two-photon effects in continuous-wave electromagnetically-induced transparency

Electromagnetically-induced transparency (EIT) in a cascade three-level scheme is studied in rubidium vapour using continuous-wave titanium sapphire lasers. A counter-propagating experimental configuration significantly reduces the coupling laser power requirements and a reduction in absorption of over 90% is observed. The hyperfine structure of the upper level is seen within the EIT feature and the application of EIT to high-resolution two-photon spectroscopy is discussed. Simultaneous measurements of the excitation to the upper state are presented and clearly show Autler-Townes splitting and power broadening.

Effects of Zeeman splitting on electromagnetically-induced transparency

Abstract An experimental and theoretical study of the effects of Zeeman splitting on electromagnetically-induced transparency in rubidium vapour has been carried out using two single-frequency, continuous-wave Ti:sapphire lasers. We show that a magnetic field, as weak as 80 Gauss, is enough to split the original, zero field, E.I.T. window into distinct sub-components. The number of sub-components observed depends directly on the two-photon selection rules. At the same time, each E.I.T. sub-component experiences a reduction in depth and an increase in broadening which is dependent on the strength of the applied magnetic field.