Rosa Henrique G, Ho Yi Wei, Verzhbitskiy Ivan, Rodrigues Manuel J F L, Taniguchi Takashi, Watanabe Kenji, Eda Goki, Pereira Vitor M, Gomes José C V
Centre for Advanced 2D Materials (CA2DM), National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore.
NUS Graduate School for Integrative Sciences and Engineering (NGS), Centre for Life Sciences (CeLS), 28 Medical Drive, Singapore, 117456, Singapore.
Sci Rep. 2018 Jul 3;8(1):10035. doi: 10.1038/s41598-018-28374-1.
We report the first detailed characterization of the sheet third-harmonic optical susceptibility, χ, of tungsten diselenide (WSe). With a home-built multiphoton microscope setup developed to study harmonics generation, we map the second and third-harmonic intensities as a function of position in the sample, pump power and polarization angle, for single- and few-layers flakes of WSe. We register a value of |χ| ≈ 0.9 × 10 m V at a fundamental excitation frequency of ℏω = 0.8 eV, which is comparable in magnitude to the third-harmonic susceptibility of other group-VI transition metal dichalcogenides. The simultaneously recorded sheet second-harmonic susceptibility is found to be |χ| ≈ 0.7 × 10 m V in very good agreement on the order of magnitude with recent reports for WSe, which asserts the robustness of our values for |χ|.
我们报告了二硒化钨（WSe₂）的面内三次谐波光学极化率χ的首次详细表征。利用为研究谐波产生而开发的自制多光子显微镜装置，我们绘制了WSe₂单层和少层薄片的二次和三次谐波强度随样品位置、泵浦功率和偏振角的变化关系。在基频激发频率ℏω = 0.8 eV时，我们记录到|χ| ≈ 0.9 × 10⁻⁹ m/V的值，其大小与其他VI族过渡金属二卤化物的三次谐波极化率相当。同时记录的面内二次谐波极化率为|χ| ≈ 0.7 × 10⁻⁹ m/V，在量级上与最近关于WSe₂的报道非常吻合，这证实了我们所测|χ|值的可靠性。
