Non-linear Thermo-Optical Properties of MoS2 Nanoflakes by Means of the Z-Scan Technique

Soghra Mirershadi,Farhad Sattari,Seyedeh Zahra Mortazavi,Afshin Alipour

doi:10.3389/fphy.2020.00096

Abstract

The nonlinear thermo-optical response of MoS2 nanoflakes was investigated using the Z-scan technique, employing TM00-mode with a CW-laser diode operating at a wavelength of 532 nm. The systems were found to exhibit a strong nonlinear response, dominated by nonlinear refraction. The effect of the thickness of the MoS2 layer, deposited on a glass substrate, on the nonlinear susceptibility was studied. Furthermore, in this study, the effects of modifying the thickness of the MoS2 nanoflakes on the nonlinear optical phenomena, such as self-focusing and self-defocusing was investigated for the first time. In all cases, the nonlinear absorption and refraction were determined. The corresponding third-order susceptibilities and second-order hyperpolarizability were calculated to be as large as 10-7 (esu) and 10-32 (esu), under laser excitation, respectively. Showing large third-order optical nonlinearity suggests the potential of the MoS2 nanoflakes in photonics applications.

Highlights

For the past few decades, the subjects that have stolen the spotlight of the theoretical and experimental interests are the linear and non-linear optical response of semiconductors [1, 2]
Non-linear optical properties of WS2 and MoS2, obtained from both open and closed aperture Z-scan techniques using a picosecond modelocked Nd: YAG laser operating at a wavelength of 1,064 nm, were investigated by Bikorimana et al [20]
The non-linear thermo-optical properties of MoS2 nanoflakes, deposited on a glass substrate with various layer thickness, using the Z-scan technique, employing CW-laser diodes operating at 532 nm wavelength, were investigated

Summary

Introduction

For the past few decades, the subjects that have stolen the spotlight of the theoretical and experimental interests are the linear and non-linear optical response of semiconductors [1, 2]. Non-linear optical properties of WS2 and MoS2, obtained from both open and closed aperture Z-scan techniques using a picosecond modelocked Nd: YAG laser operating at a wavelength of 1,064 nm, were investigated by Bikorimana et al [20]. A large two-photon absorption coefficient, β, as high as +1.91 × 10−8 cm/W was attained for Mo0.5W0.5S2, and a non-linear refractive index of n2 = −2.47 × 10−9 cm2/W was determined for the WSe2 sample.

Results

Conclusion