Applied Physics B

, Volume 90, Issue 3, pp 547–556

Nonlinear optical characteristics of self-assembled films of ZnO

Authors

    • International School of PhotonicsCochin University of Science and Technology
  • A. Deepthy
    • Amrita Institute of Medical Sciences
  • Bindu Krishnan
    • Centre for Materials for Electronics Technology
  • V.P.N. Nampoori
    • International School of PhotonicsCochin University of Science and Technology
  • P. Radhakrishnan
    • International School of PhotonicsCochin University of Science and Technology
Article

DOI: 10.1007/s00340-007-2886-1

Cite this article as:
Irimpan, L., Deepthy, A., Krishnan, B. et al. Appl. Phys. B (2008) 90: 547. doi:10.1007/s00340-007-2886-1
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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.

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© Springer-Verlag 2008