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

作者：Das Ritwick^*; Shukla Mukesh Kumar

来源：Pramana - Journal of Physics, 2014, 83(6): 985-994.

DOI：10.1007/s12043-014-0819-1

• Nonlinear refractive index
• nonlinear phase
• Gaussian beam

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 I center dot (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 +/- 1.20) x 10(-15) cm(2)/W for toluene (organic solvent) and n (2) = -(10.60 +/- 2.10) x 10(-15) cm(2)/W for an organic polymer solution (10(-4) M in toluene). By carrying out absorption measurements directly with an unfocussed Gaussian beam, we found nonlinear absorptions beta (tol) = (2.42 +/- 0.20) x 10(-13) m/W and beta (poly) = (2.79 +/- 0.24) x 10(-13) m/W which are close to the expected results.

• 出版日期2014-12