Third-order nonlinear optical response of a new epoxy-based linear polymer

An investigation was made of the nonlinear refraction of a newly synthesised polymer structure based on the diglycidyl ester of bisphenol A. The nonlinear optical chromophore was 4-aminobenzene. A degenerate two-wave interaction was used to determine the nonlinear susceptibility χ⁽³⁾ (ω; ω, — ω, ω) = (4.7 ± 2.4) × 10^–8 esu at the wavelength of the second harmonic of Nd:YAG laser radiation. An investigation of the kinetics of formation and erasure of dynamic gratings revealed the existence of two characteristic grating-erasure times: τ₁ ≤ 20 ns and τ₂ ≤ 10 μs. An analysis was made of possible mechanisms of the nonlinearity of the refractive index of the new structure. The role of the trans-cis photoisomerisation of azo compounds and the influence of these compounds on the nonlinear optical properties of the investigated polymer were noted.