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

Pramana

Mukesh Kumar Shukla¹  Ritwick Das1¹ 

[1] School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751 005, India$$

关键词: Nonlinear refractive index;    nonlinear phase;    Gaussian beam.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

We present an experimental study on measurement of nonlinear refractive index (𝑛2) of organic liquids when the thermo-optic effects manifest into large nonlinear phase shifts ($𝛥𝜙_0$) 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 𝑛2. Using this recipe, we obtain the nonlinear refractive index 𝑛2 = −(4.90 ± 1.20) × 10−15 cm2/W for toluene (organic solvent) and 𝑛2 = −(10.60 ± 2.10) × 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 𝛽tol = (2.42 ± 0.20) × 10−13 m/W and 𝛽poly = (2.79 ± 0.24) × 10−13 m/W which are close to the expected results.

【 授权许可】

Unknown