Nonlinear optical properties of BSO nanoparticles dispersed in PMMA matrix

Abstract

We present the linear and nonlinear optical properties of Bi 12SiO20 (BSO) nanocrystals of sizes 60-150 nm, synthesized using chemical solution decomposition (CSD) method. BSO nanocrystlas were characterized using XRD, UV-Vis absorption, and TEM imaging techniques. X-ray powder diffraction indicated that BSO nanocrystals have formed at the calcination temperature of 700°C. The UV-Visible absorption spectrum showed a distinct peak at 270 nm, due to the nanocrystals. The nonlinear optical properties of BSO nanocrystals dispersed in PMMA were studied using a standard open aperture Z-scan technique in the ns and ps regime using 6 ns and 30 ps laser pulses respectively. Second harmonic of Nd: YAG laser (532 nm) was used as the excitation source with incident laser intensity in the range of 0.1 - 10 GWcm-2. The BSO nanocrystals showed reverse saturable absorption (RSA) behavior in both temporal regimes. In addition to the nonlinear absorption mechanism, nonlinear scattering is also observed to contribute to the RSA behavior in both the time regimes. Of both the pulse durations, nonlinear scattering was observed higher with the 6 ns excitation compared to the 30 ps excitation. © 2010 SPIE.