Third-order nonlinear optical response of a new linear polymer with 4-aminoazobenzene

Nonlinear refraction in a new polymer material based on diglycidylether of bisphenol-A and containing 4-aminoazobenzene covalently attached to the polymer chains have been studied. The material was shown to exhibit fast nonlinear response (relaxation time about 20 ns, chi((3)) = 5 x 10(-8) esu) together with slow one (relaxation time of the order of tens of hours). This makes it possible to record fast and long life (quasi stationary) phase holograms. An analysis of possible mechanisms for the refractive index nonlinear behavior in the new structure is presented. In particular, a role of electronic, thermal, orientation, and isomerization processes is discussed. It was for the first time shown that the rotational and inversion mechanisms of the cis --> trans isomerization of the azo-compounds have determinative effect upon kinetics of the nonlinear refractive index relaxation. For the rotational mechanism the relaxation time was found to be 10(-4) s meanwhile for the inversion mechanism it was 10(5) s.