Impact of brilliant green dye on structural, linear, and third-order nonlinear optical properties of poly(vinyl alcohol) polymer composites for optoelectronic applications

The structural, linear, and nonlinear optical (NLO) characteristics of solvent cast brilliant green (BG) dye-doped poly(vinyl alcohol) (PVA) composite films were investigated. The composites show strong linear absorption spectra at 635 nm in the visible region. The fluorescence emission wavelength shifted from 665 to 678 nm and the fluorescence anisotropy (r) was estimated. The energy transfer mechanism was explained by fluorescence lifetime decay curves. NLO properties, such as nonlinear refractive index (n(2)), two-photon absorption (beta), and third-order nonlinear susceptibility chi((3)), were studied using Z-scan technique with He-Ne laser at 633 nm. The influence of dye doping switched the nonlinear absorption from reverse saturable to saturable absorption and the obtained beta, n(2), and chi((3)) are in the order of similar to 10(-3) cm W-1, 10(-8) cm(2) W-1, and 10(-6) esu, respectively, for all samples. The high fluorescence emission and NLO switching behavior show that the BG/PVA composites could be suitable for optoelectronic and photonic applications.