Open AccessEffects of substrates on the nonlinear optical responses of two-dimensional materials
Author(s) -
Jianhua Zeng,
Jinxiang Li,
Hui Li,
Qiao-Feng Dai,
Shaolong Tie,
Sheng Lan
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.031817
Subject(s) - materials science , dielectric , electric field , second harmonic generation , substrate (aquarium) , optoelectronics , optics , layer (electronics) , reflection (computer programming) , thin film , nanotechnology , laser , oceanography , physics , quantum mechanics , computer science , programming language , geology
We investigated numerically and experimentally the achievement of strongly localized electric field and significantly enhanced second harmonic generation (SHG) in two-dimensional (2D) materials by using dielectric-metal hybrid substrates. Based on the theory of thin film interference, it was revealed that the strongest localization of electric field in a 2D material, which corresponds to the largest absorption in the metal film, could be achieved by minimizing the reflection of the combined structure (i.e., 2D material + hybrid substrate) because the transmission through the combined structure was negligible. By using MoS₂ as an example, it was demonstrated that a SHG enhancement factor of ~6 could be achieved in the 17-nm-thick MoS₂ layer on an Au/SiO₂ substrate as compared with the single-layer MoS₂ on the commonly used SiO₂/Si substrates with highly efficient SHG. By employing a SiO₂-SnO₂/Ag/SiO₂ substrate in which a 20-nm-thick dielectric film of SiO₂-SnO₂ was inserted in between the MoS₂ layer and the Ag film, a SHG enhancement factor as large as ~18 could be realized in the 9-nm-thick MoS₂ layer. Numerical simulations based on the finite-difference time-domain technique were employed to derive the enhancement factors for SHG and it was revealed that for thick MoS₂ layers the SHG intensity is dominated mainly by the localization of electric field induced by the dielectric-metal hybrid substrates. The dependence of the SHG enhancement factor on the thickness of the MoS₂ layer was found to be modified when the dielectric-metal hybrid substrates were adopted.