title: Excited-state enhancement of third-order optical nonlinearities: photodynamics and characterization.
abstract: Based on the simplified five-level rate-equation theory, we investigate the hybrid third-order optical nonlinear processes which combine the instantaneous nonlinearity and the one-photon absorption induced excited-state nonlinearity. We obtain the analytical third-order nonlinear absorption and refraction coefficients originating from the singlet and triplet excited-state effects. We explore the photodynamic process and give the corresponding level diagram in the nanosecond, picosecond, and femtosecond regimes. We develop the pulse-duration-dependent Z-scan theory for characterizing the simultaneous instantaneous nonlinearity and cumulative effect of the excited-state nonlinearity. We also demonstrate the validity of the presented theory to analyze the experimental results.
authors.affiliation: School of Physics and Key Laboratory of Weak Light Nonlinear Photonics, Nankai University, Tianjin, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Gu
authors.forename: Kai
authors.initials: K
authors.lastname: Lou
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Yongnan
authors.initials: Y
authors.lastname: Li
authors.forename: Hui-Tian
authors.initials: HT
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Ji
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D017785:Photons; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation