Effect of inhomogeneous line broadening due to molecular collisions on a two-level system interacting with a high-intensity electromagnetic field

In this work, we present a formalism to study the optical properties on a two-level molecular system interacting with the electromagnetic field. We consider a model where molecular collisions induce frequency shifts that lead to a modulation of the transition frequency. By considering a perturbative treatment of the field acting on the two-level system, the optical conventional Bloch equations were resolved and averaged over all realizations of the stochastic variables, using both Gaussian and Lorentzian distributions. Optical property surfaces indicating its dependence on the detuning factor, the perturbed field and parameters of the distributions are reported. In this work, quantitative results for the optical response of standard molecular models are presented, i.e., organic dyes, under the influence of moderate strong fields. The results reflected the fact that not only the noise intensities are important in the stochastic modulation of the optical signals (as is usually assumed) but also the noise relaxation times plays a role that cannot be neglected. (c) 2005 Elsevier B.V. All rights reserved.