衬底对MoSe_2的二次谐波强度的影响

Effects of Substrates on Second Harmonic Generation of MoSe_2

采用时域有限差分法研究了SiO_2/Si衬底、Au/SiO_2衬底、SiO_2-SnO_2/Ag/SiO_2衬底上MoSe_2的反射、透射、吸收和二次谐波增强因子随厚度的依赖关系。计算了各种介质-金属衬底上MoSe_2的电场分布曲线,结果表明块体MoSe_2的二次谐波的增强主要源于介质-金属衬底诱导的电场局域效应,并由薄膜干涉原理进行了解释。通过反射谱的模拟计算出了Au/SiO_2衬底、SiO_2-SnO_2/Ag/SiO_2衬底上16nm和9nm MoSe_2的色品坐标,便于实验中对样品的表征。理论计算结果预示着MoSe_2与MoS_2一样也能用来在实验上实现光信息存储。

The reflection,tranmission,absorption and enhancement factors for SHG of the MoSez layers with different thicknesses on SiOz/Si, Au/SiOz and SiO2-SnOz/Ag/SiOz substrates were calculated by using the finite-difference time-domain technique. The electric field distributions inside the MoSe2 layers on different substrates were calculated and it was revealed that for thick MoSe2 layers the SHG intensity is dominated mainly by the localization of electric field induced by the dielectric-metal hybrid substrates. The localization was analyzed by using the theory of thin film interference. The corresponding chromaticity coordinates of the 16-nm-thick MoSe2 layer on the Au/SiOz substrate and the 9-nm-thick MoSe2 layer on the SiOz- SnOz/Ag/SiO2 substrate were derived to facilitate the characterization of samples in experiments. Theoretical results indicate that MoSe2 can also be used to realize opticaI information stor- age besides MoS2.