Influence of correlated stochastic perturbations on the nonlinear optical properties of a dimer

The problem of correlated diagonal fluctuations is treated in the particular case of a dimer. Specifically, we analyze the influence of the correlation existing between the fluctuations on different sites. The local fluctuations induce a frequency modulation on the individual monomers. When these fluctuations are correlated, the internal dynamics of the dimer is altered. As a consequence, these intersite correlations give an additional contribution to the linear and nonlinear optical responses of the dimer. While this process has been discussed previously for {δ}-function-correlated Gaussian-Markovian processes, we consider here the non-{δ}-function-correlated case. The linear absorption spectrum and the third-order susceptibility in a degenerate-four-wave-mixing experiment are considered in order to emphasize the role of the correlated fluctuations in the linear and nonlinear regimes, respectively.