In this paper, we present the third harmonic generation response of Znq₂ (Bis-(8-hydroxyquinolinato)zinc), Cuq₂ (8-Hydroxyquinoline copper(II)), and Alq₃ (Tris-(8-hydroxyquinoline)aluminum) organometallic compounds. An experiment was conducted for s and p polarizations of incident beam, using the Maker fringes technique. The third order nonlinear susceptibility χ(3) was estimated using the Kubodera and Kobayashi comparative model, on the grounds that presented compounds exhibit high linear absorption of the generated third harmonic wavelength (355 nm). These complexes were deposited as thin films using the physical vapor deposition (PVD) method. Investigated complexes vary in terms of the coordination center and number of quinoline ligands, which visibly influence their nonlinear response. The global hybrid B3LYP functional with the basis set 6-31G(d) was used in computing the linear and non-linear optical properties. The computed γtot value (8765.36 × 10-36 esu for Cuq₂) is superior to that of methylene blue (γ = 32.00 × 10-36 esu). The calculated theoretical values were found to be in good agreement with the experimental results.
Keywords: DFT/B3LYP/6-31G(d) calculations; coordination complexes; nonlinear optic (NLO); organometallic compounds; physical vapor deposition (PVD); third harmonic generation (THG).