The Behavior of CARS in Anti-Stokes Raman Converters Operating at Exact Raman Resonance

In this paper, we present a model that fully describes the quasi-stationary behavior of coherent anti-Stokes Raman scattering (CARS) in an anti-Stokes Raman converter operating at exact Raman resonance. We demonstrate that the CARS mechanism actually comprises two opposite and competing interactions, which respectively create and annihilate phonons in the Raman medium. Furthermore, we show that both the phase mismatch of the CARS four-wave mixing process and the level of pump depletion determine which of these two interactions takes place along the converter path length. In addition, we demonstrate that our CARS model is fully in line with seemingly contradictory findings in Raman conversion experiments. Finally, we discuss the fundamental differences between our CARS interpretation and the CARS models presented earlier.