[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Impact of Strain on the Second-Harmonic Generation in Transition Metal Dichalcogenide Monolayers

摘要： Second-harmonic generation (SHG) is a powerful measurement technique to analyse the symmetry properties of crystals. Mechanical strain can reduce the symmetry of a crystal and even weak strain can have an immense impact on the SHG intensity along different polarization directions [1]. The impact of strain on the SHG can be modelled with a second-order nonlinear photoelastic tensor [2,3]. We find that the photoelastic tensors depends highly on the excitation wavelength. We investigated the influence of strain on SHG for MoS2, MoSe2, WS2, and WSe2 monolayers. In order to quantify the strain induced anisotropy in the polarization resolved SHG we define two parameters. The Distortion (cid:1830) = (cid:4672), which is the ratio of the minima to the maxima of the envelope function of the polarization resolved SHG and the Intensity (cid:1835) = (cid:2024)((cid:1827)(cid:2870) + (cid:1828)(cid:2870)), which is the integral of the SHG intensity over all polarization directions. Our investigation allows for highly sensitive, non-invasive strain matrix imaging at the submicron scale as well as strain engineering of the conversion efficiency of SHG for all investigated materials.