Experimental and theoretical investigation of third-order nonlinear optical properties of azo dye 1-(2, 5-Dimethoxy-phenylazo)-naphthalen-2-ol by Z-scan technique and quantum chemical computations

Abstract

The structural and optical characterization of the 1-(2,5-Dimethoxy-phenylazo)-naphthalen-2-ol were analyzed experimentally by FT-IR, FT-Raman and UV-visible spectroscopic technique and theoretical studies by density functional theory method. The charge transfer interactions leading to nonlinear properties taking place in the molecule can be studied by HOMO-LUMO analysis and natural bond orbital analysis. The second-order hyperpolarizability (γ) was calculated at DFT level and it show good agreement with the experimental result. The third-order nonlinear optical parameters such as nonlinear refractive index (n2), nonlinear absorption coefficient (β), real, imaginary parts of third-order susceptibility (χ(3)) and second-order hyperpolarizability (γ) were measured experimentally by closed and open aperture Z-scan technique. Z-scan measurements were performed using Q-switched Nd: YAG laser with 5 ns pulses at 532 nm with different dye concentrations and intensities. The open and closed aperture Z-scan measurements confirms, the dye exhibit saturable absorption property and positive nonlinearity. The result also shows that there is an increasing trend in the values of the nonlinear refractive index and the third order nonlinear susceptibility while increasing concentration. These attractive third-order nonlinear results indicated that 1-(2,5-Dimethoxy-phenylazo)-naphthalen-2-ol have potential applications in optoelectronics and photonics.