Table of Contents
ISRN Nanomaterials
Volume 2013, Article ID 327575, 6 pages
Research Article

Ag Nanoparticles: Experimental Study of Sign Identification of Nonlinear Refractive Index by Moiré Deflectometry and Z-Scan Methods

1Department of Physics, Faculty of Sciences, Roudehen Branch, Islamic Azad University, Roudehen 3973188981, Iran
2Optical Measurement Central Lab, Amirkabir University of Technology, Tehran 4413-15875, Iran
3Department of Physics, University of Tehran, Tehran 1439955961, Iran

Received 5 July 2013; Accepted 30 July 2013

Academic Editors: R. Azimirad and J. Shen

Copyright © 2013 Adeleh Granmayeh Rad et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Two different methods are presented for the sign identification of nonlinear refractive index ( ) of Ag colloidal nanoparticles which are based on nonscanning Moiré deflectometry and Z-scan. In the Moiré deflectometry setup, two lasers are used, one is used as pump laser which causes thermal nonlinear effects in the sample, and the second one is used as the probe laser for monitoring these effects by Moiré deflectometry system. By observing the deflected Moiré fringes, we can determine the sign of nonlinear refractive index in real time, and there would be no need for calibration or complicated calculations. The second technique for sign identification is Z-scan. In this technique, a CW 532 nm second harmonic Nd:YAG laser with a beam power of 55 mW is used as the excitation source. Results show that the nonlinear refractive index is negative for Ag nanoparticles in pure water by both methods.