Open AccessOff-resonance and non-resonant dispersion of Kerr nonlinearity for symmetric molecules [Invited]
Author(s) -
George I. Stegeman,
Mark G. Kuzyk,
Dimitris G. Papazoglou,
S. Tzortzakis
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.022486
Subject(s) - physics , excited state , resonance (particle physics) , photon , dispersion (optics) , refractive index , ground state , symmetry (geometry) , atomic physics , optics , quantum mechanics , interference (communication) , nonlinear system , channel (broadcasting) , geometry , mathematics , electrical engineering , engineering
The exact formula is derived from the "sum over states" (SOS) quantum mechanical model for the frequency dispersion of the nonlinear refractive index coefficient n₂ for centrosymmetric molecules in the off-resonance and non-resonant regimes. This expression is characterized by interference between terms from two-photon transitions from the ground state to the even-symmetry excited states and one-photon transitions between the ground state and odd-symmetry excited states. When contributions from the two-photon terms exceed those from the one-photon terms, the non-resonant intensity-dependent refractive index n₂>0, and vice versa. Examples of the frequency dispersion for the three-level SOS model are given. Comparison is made with other existing theories.