A new experimental method for observing chromophore relaxation dynamics in nonlinear optical polymer systems is described. The method is similar to dielectric relaxation measurements, which probe the linear susceptibility χ<sup>(1)</sup>, but this new method is chromophore selective and probes the nonlinear susceptibility χ<sup>(2)</sup> in the frequency domain, monitoring second-harmonic generation during the application of a strong ac electric field. The out-of-phase component of χ<sup>(2)</sup> exhibits behavior similar to that of the loss component in dielectric relaxation and is shown to be unaffected by electric-field-induced third-order effects. The relation to dielectric relaxation is discussed, and stretched exponential parameters are extracted for a Disperse-Red-1/poly(methyl methacrylate) guest–host system.
© 1998 Optical Society of America
(060.2330) Fiber optics and optical communications : Fiber optics communications
(160.5470) Materials : Polymers
(190.4400) Nonlinear optics : Nonlinear optics, materials
(250.5300) Optoelectronics : Photonic integrated circuits
W. N. Herman and J. A. Cline, "Chielectric relaxation: chromophore dynamics in an azo-dye-doped polymer," J. Opt. Soc. Am. B 15, 351-358 (1998)