Linear and Third-Order Optical Responses of a Dendrimerically Coupled Oscillator System

抄録

Characteristics of linear and third-order optical responses are investigated for a system consisting of identical oscillators coupled dendrimerically with each other. Each oscillator is assumed to be harmonic and optically excitable. Dependences of these responses on the size of the dendrimeric system are examined with numerical calculations on the oscillator strength and the third-order polarizability. It is shown that the total oscillator strength increases linearly with the number of the oscillators, whereas the third-order polarizability increases far more steeply. From the microscopic viewpoint, there are two types of processes that contribute to the third-order polarization of a molecular aggregate system: One type is the induction of the third-order polarization at each molecular unit, and the other is the cooperative participation of the units. Contributions of these processes to the total polarization are examined. It is then shown that the relative importance of the latter type increases as the size of the dendrimeric system gets large.