• Measurement of nonlinear refractive index in open-aperture 𝑍-scan experiments

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      https://www.ias.ac.in/article/fulltext/pram/083/06/0985-0994

    • Keywords

       

      Nonlinear refractive index; nonlinear phase; Gaussian beam.

    • Abstract

       

      We present an experimental study on measurement of nonlinear refractive index ($n_2$) of organic liquids when the thermo-optic effects manifest into large nonlinear phase shifts ($\Delta\phi_0$) in an open-aperture 𝑍-scan configuration. Although we do not obtain the familiar peak–valley normalized transmittance curve as in the case of closed-aperture 𝑍-scan technique, we use a theoretical model using Gaussian beam decomposition (GD) technique to estimate the value of $n_2$. Using this recipe, we obtain the nonlinear refractive index $n_2 = −(4.90 \pm 1.20) \times 10^{−15}$ cm2/W for toluene (organic solvent) and $n_2 = −(10.60 \pm 2.10) \times 10^{−15}$ cm2/W for an organic polymer solution (10$^{−4}$ Min toluene). By carrying out absorption measurements directly with an unfocussed Gaussian beam, we found nonlinear absorptions $\beta_{\text{tol}} = (2.42 \pm 0.20) \times 10^{−13}$ m/W and $\beta_{\text{poly}} = (2.79 \pm 0.24) \times 10^{−13}$ m/W which are close to the expected results.

    • Author Affiliations

       

      Ritwick Das1 Mukesh Kumar Shukla1

      1. School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751 005, India
    • Dates

       
  • Pramana – Journal of Physics | News

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