OPTICAL 2ND-HARMONIC GENERATION AS A PROBE OF THE TEMPERATURE-DEPENDENCE OF THE DISTRIBUTION OF SITES IN A POLY(METHYL METHACRYLATE) POLYMER DOPED WITH DISPERSE RED-1 AZO-DYE

We have applied electric-field-induced optical second-harmonic generation to measure the distribution of chromophore sites in a dye-doped polymer [disperse red 1 in poly (methyl methacrylate)] in terms of the standard α and β parameter, that is, the decay rate and the breadth parameter. These parameters have been measured from 100 to 430 K and are modeled with a smooth function over that temperature range. Over a narrow region of temperature where second-harmonic data from other groups exist, we find that our temperature dependence of β is in excellent agreement with these other experiments. In principle, our method can be applied to any glassy polymer to characterize the temperature dependence of the distribution of nonlinear-optical dye sites. © 1995 American Institute of Physics.