Response of a Two-Level System Driven by Two Strong Fields

Abstract

The absorption and dispersion response of a driven NMR two-level system in diamond is investigated using Raman heterodyne technique for which both pump and probe fields are strong. Up to 11 multiphoton resonances in dispersion and up to three-photon gain without inversion in absorption are observed. These gain features can be attributed to inversion between dressed states. Futhermore, a gain feature for which there is no inversion in either bare or dressed states is observed. The results are in good agreement with calculations.