Linear and nonlinear optical properties of luminescent ZnO nanoparticles embedded in PMMA matrix

• Published in: Optics communications 2010-07, Vol.283 (14), p.2908-2913
• Main Authors: Sreeja, R., John, Jobina, Aneesh, P.M., Jayaraj, M.K.
• Format: Article
• Language: English
• Subjects: Apertures; Beam trapping, self-focusing and defocusing; self-phase modulation; Constraining; Devices; Dispersion; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Nanoparticles; Nonlinear optics; Nonlinearity; Optical susceptibility, hyperpolarizability; Optics; Physics; Polymethyl methacrylates; Zinc oxide
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2010.02.044

ZnO nanoparticles embedded in the PMMA matrix were prepared by wet chemical synthesis. The optical band gap of the ZnO nanoparticles decreases with increase in NaOH concentration. The photoluminescence spectra of the ZnO colloids show strong UV, green and blue emissions. The optical absorptive nonlinearity of the ZnO:PMMA composites was analyzed using an open aperture Z-scan technique which shows optical limiting type nonlinearity due to the two photon absorption in ZnO. The efficiency of limiting is found to increase with decrease in the band gap. ZnO:PMMA shows a negative value for nonlinear refractive index n 2 and the magnitude of n 2 increases with decrease of band gap. Stability as well as the mechanical properties of the nanoparticles embedded in the PMMA matrix makes it more suitable for device fabrication as compared to the ZnO nanoparticles dispersed in solution.