Nonlinear optical responses of nanoparticle-polymer composites incorporating organic (hyperbranched polymer)-metallic nanoparticle complex

Abstract

We report on experimental studies of the nonlinear optical properties of nanocomposites consisting of organic (hyperbranched polymer)-metallic (Au or Pt) nanoparticle complex embedded in polymer films. Open-aperture and closed-aperture z-scan techniques are used to measure the effective third-order nonlinear optical susceptibilities χeff(3) of the composites under picosecond laser radiation at a wavelength of 532 nm. The relative sign of the real and imaginary parts of χeff(3) could be explained qualitatively by the Kramers–Kronig relation. We also determined the third-order nonlinear optical susceptibilities of Au and Pt nanoparticles estimated from the measured values for χeff(3) to be (−5.48+4.76i)×10−8 esu and (4.41−0.65i)×10−6 esu, respectively, at 532 nm with a help of the Maxwell–Garnett model.