The dynamical behavior of a two-level atom under the influence of two intense pump beams is examined. Exact equations for the nonlinear susceptibilities to all orders in the field strengths are derived. Numerical results for the nonlinear susceptibilities giving the absorption of the radiation from either of the pump beams and the generation of the four-wave mixing signal are given. The susceptibility for four-wave mixing, in addition to showing various saturation peaks, shows a peak at ω1 = ω2 even in the case of radiative relaxation. Higher-order multiphoton peaks in the absorption spectra are found to be extremely sensitive to the temporal fluctuations in the pumps.
© 1984 Optical Society of America
G. S. Agarwal and N. Nayak, "Multiphoton processes in two-level atoms in two intense pump beams," J. Opt. Soc. Am. B 1, 164-168 (1984)