Excitons in confined geometries: Size scaling of nonlinear susceptibilities
نویسندگان
چکیده
The third-order nonlinear optical response of one-dimensional molecular aggregates of arbitrary size is calculated using equations of motion for single-exciton and two-exciton variables. These equations map the system onto the dynamics of N( N + I)/2 coupled nonlinear oscillators, where N is the number of molecules in the aggregate. The scaling of the generalized third-order hyperpolarizability yc3’ with N is analyzed in detail. The complete wave vector and frequency dependence of yc3’ is maintained and cooperative radiative decay (superradiance) is incorporated. Comparison is made with the density-matrix approach which provides a fully time-ordered expression.
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