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Center for Nonlinear Studies |
Abstract: The growing potential for utilizing two-photon absorption (TPA) applications has initiated a wave of theoretical and experimental investigations towards the design of organic chromophores with strong TPA optical response. Recent studies have elucidated the ways of manipulating TPA cross-sections and energies of organic dyes utilizing complex interplay between conjugation length, substitution and branching. Theoretical models providing information about the excited state electronic structure are especially valuable for understanding the mechanisms of two photon absorption processes in conjugated molecules, and for the further material design. We utilize the time-dependent density functional theory (TD-DFT) in combination with quasi-particle formalism for nonlinear optical polarizabilities to obtain insight into the origins of the physical phenomena and analyze the trends leading to large TPA responses of a number of organic chromophores. This talk will include a short overview of the TPA phenomena, applications and theoretical description. A general picture of the TPA-active organic molecules will be presented with the focus on the effect of symmetric and asymmetric donor/acceptor substitution and branching.