Article

Applied Physics B

, Volume 90, Issue 3, pp 547-556

First online:

Nonlinear optical characteristics of self-assembled films of ZnO

  • Litty IrimpanAffiliated withInternational School of Photonics, Cochin University of Science and Technology Email author 
  • , A. DeepthyAffiliated withAmrita Institute of Medical Sciences
  • , Bindu KrishnanAffiliated withCentre for Materials for Electronics Technology
  • , V.P.N. NampooriAffiliated withInternational School of Photonics, Cochin University of Science and Technology
  • , P. RadhakrishnanAffiliated withInternational School of Photonics, Cochin University of Science and Technology

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Abstract

In the present work, we have investigated the nonlinear optical properties of self-assembled films formed from ZnO colloidal spheres by z-scan technique. The sign of the nonlinear component of refractive index of the material remains the same; however, a switching from reverse saturable absorption to saturable absorption has been observed as the material changes from colloid to self-assembled film. These different nonlinear characteristics can be mainly attributed to ZnO defect states and electronic effects when the colloidal solution is transformed into self-assembled monolayers. We investigated the intensity, wavelength and size dependence of saturable and reverse saturable absorption of ZnO self-assembled films and colloids. Values of the imaginary part of third-order susceptibility are calculated for particles of size in the range 20–300 nm at different intensity levels ranging from 40 to 325 MW/cm2 within the wavelength range of 450–650 nm.