Relaxation phenomena in polymer nonlinear optical materials

The isothermal decay of the second-order nonlinear optical susceptibility of a guest-host azo dye methacrylate film was measured by second-harmonic generation at a series of temperatures. The decay curves were fit to Williams–Watt–Kohlrausch stretched exponentials. The activation energies and pre-exponential factors were found to agree with those derived from nonisothermal electric-field-induced second-harmonic generation measurements on similar films. It is concluded that a common underlying process involving a distribution of local relaxations governs the film behavior.