Molecular multiphoton excitation by phase coherent pulse pairs

We theoretically analyze the absorption of media excited by a pair of coherent pulses, as a function of their relative phase, in conditions of multiphoton resonance and negligible dephasing. It is shown that, the periodicity of transmission vs delay and phase, is characteristic of the nature and order of the process. Also a multilevel system may evolve from pure multiphoton resonance to cascade resonance under specific conditions depending on the detunings of the levels involved.