title: Microscopic cascading of second-order molecular nonlinearity: New design principles for enhancing third-order nonlinearity.
abstract: Herein, we develop a phenomenological model for microscopic cascading and substantiate it with ab initio calculations. It is shown that the concept of local microscopic cascading of a second-order nonlinearity can lead to a third-order nonlinearity, without introducing any new loss mechanisms that could limit the usefulness of our approach. This approach provides a new molecular design protocol, in which the current great successes achieved in producing molecules with extremely large second-order nonlinearity can be used in a supra molecular organization in a preferred orientation to generate very large third-order response magnitudes. The results of density functional calculations for a well-known second-order molecule, (para)nitroaniline, show that a head-to-tail dimer configuration exhibits enhanced third-order nonlinearity, in agreement with the phenomenological model which suggests that such an arrangement will produce cascading due to local field effects.
authors.affiliation: The Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo, Buffalo, New York 14260, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Baev
authors.forename: Jochen
authors.initials: J
authors.lastname: Autschbach
authors.forename: Robert W
authors.initials: RW
authors.lastname: Boyd
authors.forename: Paras N
authors.initials: PN
authors.lastname: Prasad