Saved in:
| Main Authors: | , , , , , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2026
|
| Subjects: | |
| Online Access: | https://arxiv.org/abs/2605.21231 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866913149718888448 |
|---|---|
| author | Wang, Yiduo Lu, Yao Chen, Changshen Liao, Xiaotong Fan, Siyu Wang, Zhenyu Liu, Yaotian Du, Subi Jia, Yingze Zhu, Ye Wang, Yingwei He, Jun Liu, Song Ruan, Jiawei Chen, Zhen Lin, Kai-Qiang Xu, Yang |
| author_facet | Wang, Yiduo Lu, Yao Chen, Changshen Liao, Xiaotong Fan, Siyu Wang, Zhenyu Liu, Yaotian Du, Subi Jia, Yingze Zhu, Ye Wang, Yingwei He, Jun Liu, Song Ruan, Jiawei Chen, Zhen Lin, Kai-Qiang Xu, Yang |
| contents | The stacking configuration of two-dimensional materials critically governs their optical and electronic responses. Monolayer transition-metal dichalcogenides (TMDC) lack inversion symmetry and exhibit exciton-enhanced second-harmonic generation (SHG). In TMDC bilayers, 60° (0°) stacking is conventionally expected to suppress (enhance) SHG owing to destructive (constructive) interference of the layer-resolved nonlinear polarizations. Here, we report an unconventional destructive SHG interference in nearly 0°-stacked (AA-stacked) MoTe2/WSe2 heterobilayers using two independent probes: atomic-resolution imaging and stacking-sensitive exciton hybridization measurements. Supported by ab initio GW and Bethe-Salpeter equation calculations, we show that distinct two-photon resonances associated with the WSe2 C exciton and the MoTe2 D exciton generate a nearly $π$ phase difference ($Δϕ$) in their second-order nonlinear susceptibilities $χ^{(2)}$, leading to the anomalous destructive interference. We further demonstrate that in small-angle twisted MoTe2/WSe2, the SHG polarization state is governed by the interplay between twist angle $α$ and phase difference $Δϕ$, and can be mapped onto trajectories on the Poincaré sphere. At excitation energies satisfying $Δϕ$ + 3$α$ = 180°, the SHG output becomes nearly circularly polarized (ellipticity ~ 0.91) and undergoes an abrupt 90° azimuthal rotation, corresponding to a geometric polarization singularity in the parameter space. Our findings open new routes for exciton-resonance engineered nonlinear photonics and stacking-resolved optical functionality in moiré materials. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_21231 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Destructive interference of second harmonic generation in AA stacked MoTe$_2$/WSe$_2$ Wang, Yiduo Lu, Yao Chen, Changshen Liao, Xiaotong Fan, Siyu Wang, Zhenyu Liu, Yaotian Du, Subi Jia, Yingze Zhu, Ye Wang, Yingwei He, Jun Liu, Song Ruan, Jiawei Chen, Zhen Lin, Kai-Qiang Xu, Yang Mesoscale and Nanoscale Physics The stacking configuration of two-dimensional materials critically governs their optical and electronic responses. Monolayer transition-metal dichalcogenides (TMDC) lack inversion symmetry and exhibit exciton-enhanced second-harmonic generation (SHG). In TMDC bilayers, 60° (0°) stacking is conventionally expected to suppress (enhance) SHG owing to destructive (constructive) interference of the layer-resolved nonlinear polarizations. Here, we report an unconventional destructive SHG interference in nearly 0°-stacked (AA-stacked) MoTe2/WSe2 heterobilayers using two independent probes: atomic-resolution imaging and stacking-sensitive exciton hybridization measurements. Supported by ab initio GW and Bethe-Salpeter equation calculations, we show that distinct two-photon resonances associated with the WSe2 C exciton and the MoTe2 D exciton generate a nearly $π$ phase difference ($Δϕ$) in their second-order nonlinear susceptibilities $χ^{(2)}$, leading to the anomalous destructive interference. We further demonstrate that in small-angle twisted MoTe2/WSe2, the SHG polarization state is governed by the interplay between twist angle $α$ and phase difference $Δϕ$, and can be mapped onto trajectories on the Poincaré sphere. At excitation energies satisfying $Δϕ$ + 3$α$ = 180°, the SHG output becomes nearly circularly polarized (ellipticity ~ 0.91) and undergoes an abrupt 90° azimuthal rotation, corresponding to a geometric polarization singularity in the parameter space. Our findings open new routes for exciton-resonance engineered nonlinear photonics and stacking-resolved optical functionality in moiré materials. |
| title | Destructive interference of second harmonic generation in AA stacked MoTe$_2$/WSe$_2$ |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2605.21231 |