Research

Nonlinear optical response of Mg/MgO structures prepared by laser ablation method

Department of physics, East Tehran Branch, Islamic Azad University, Tehran, Iran

^a +989193117542 f_abrinaey@yahoo.com

Received: 15 February 2017
Accepted: 20 April 2017

Abstract

Background: Investigation of new materials plays an important role in advancing the field of optoelectronics.

Methods: In this work, Mg/MgO microstructures were prepared by Nd-YAG laser (λ= 1064 nm) ablation of magnesium target in acetone. For the first time, the nonlinear optical properties of square Mg/MgO microstructures were investigated by using the Z-scan technique with nanosecond Nd-YAG laser at 532 nm.

Results: The XRD analysis approved the formation of Mg/MgO microstructures. The energy band gap of Mg/MgO microstructures was calculated to equal 2.3 eV from UV-Vis spectrum. The ablated materials were ejected into acetone as structures with an average size of 1-1.5 μm. The nonlinear absorption coefficient, β, and nonlinear refractive index, n₂, for Mg/MgO microstructures at the laser intensity of 1.1 × 10⁸ W/cm2 were measured to be 1.15 × 10^–8 cm/W and 8.2 × 10^-13 cm²/W, respectively. In order to investigate size particles and liquid medium effects, the nonlinear optical parameters, β and n₂ of Mg/MgO nanostructures synthesized by laser ablation of magnesium target in isopropanol also were calculated and it was found these parameters are an order of magnitude larger than the values for the β and n₂ of Mg/MgO microstructures synthesized in acetone. The third-order nonlinear optical susceptibility, χ⁽³⁾, of Mg/MgO microstructures and nanostructures were measured in order of 10^-6 and 10^-5 esu, respectively.

Conclusions: The results show that Mg/MgO structures synthesized in acetone and isopropanol have negative nonlinearity as well as good nonlinear absorption at 532 nm and these magnesium-based structures have the potential applications in the nonlinear optical devices.