AI 中文总结
本研究利用铁电性控制MoS₂/LiNbO₃界面的光掺杂，实现单层MoS₂中二次谐波产生的域选择性增强，提升SHG强度约70%，为非线性光子功能提供新调控手段。
AI 中文摘要
将二维半导体与铁电材料结合的混合异质结构为主动调控纳米尺度的光-物质相互作用提供了通用途径。本研究报道了集成周期性极化铌酸锂（LiNbO₃）的单层二硫化钼（MoS₂）中，全光、光诱导的二次谐波产生（SHG）域选择性调控。空间分辨SHG成像显示，单层MoS₂的非线性光学响应受衬底铁电畴图案调控，相反极化畴间存在显著的SHG对比度，且该对比度明显依赖于激发波长和入射光功率。通过对比MoS₂单层中可发生或不发生光驱动光掺杂的铁电畴，直接评估了载流子密度对非线性光学响应的作用。研究发现，MoS₂/LiNbO₃界面处铁电极化控制的光掺杂可增强有效二阶极化率χ²，在共振激发条件下使SHG强度提升约70%。从头计算证实，电荷掺杂会改变MoS₂的电子能带结构，并在共振区域强烈影响χ²，为实验观测到的调制提供了微观层面的支撑。研究结果表明，光强度与铁电性的结合是调控二维材料能带结构和实现可重构非线性光学响应的有力手段，为集成混合平台中的可编程频率转换、智能光调制器及先进非线性光子功能开辟了路径。
英文摘要
Hybrid heterostructures combining two-dimensional semiconductors with ferroelectric materials offer a versatile route to actively control light-matter interactions at the nanoscale. Here, we report all-optical, light-induced domain-selective control of second-harmonic generation (SHG) in monolayer molybdenum disulfide (MoS$_2$) integrated with periodically poled lithium niobate (LiNbO$_3$). Spatially resolved SHG imaging reveals a pronounced modulation of the nonlinear optical response of monolayer MoS$_2$ governed by the ferroelectric domain pattern of the underlying substrate. A strong SHG contrast is observed between domains of opposite polarization, with a marked dependence on both the excitation wavelength and the incident optical power. The comparison between ferroelectric domains that either enable or do not exhibit light-driven photodoping in the MoS$_2$ monolayer provides a direct assessment of the role of carrier density in the nonlinear optical response. We find that ferroelectric-polarization-controlled photodoping at the MoS$_2$/LiNbO$_3$ interface enhances the effective second-order susceptibility, $χ^2$, producing an increase in SHG intensity of up to ~70% under resonant excitation conditions. Ab initio calculations corroborate that charge doping modifies the electronic band structure of MoS$_2$ and strongly affects $χ^2$ in the resonant regime, providing microscopic support for the experimentally observed modulation. The results highlight the combination of light intensity and ferroelectricity as a powerful knob for band-structure modulation in 2D materials and reconfigurable nonlinear optical responses, opening pathways toward programmable frequency conversion, smart light modulators, and advanced nonlinear photonic functionalities in integrated hybrid platforms.
