Engineering Nonlinear Optical Responses via Inversion Symmetry Breaking in Bilayer Bi2Se3
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2026
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| author | Sharma, Vineet Kumar Okullo, Alana Ghosh, Barun Bansil, Arun Chowdhury, Sugata |
| author_facet | Sharma, Vineet Kumar Okullo, Alana Ghosh, Barun Bansil, Arun Chowdhury, Sugata |
| contents | Paucity of naturally occurring noncentrosymmetric materials is stimulating growing interest in engineered two-dimensional systems for nonlinear optical applications. Here, we show that breaking inversion symmetry in centrosymmetric bilayer Bi$_2$Se$_3$ through twisting, point-defect insertion, or the application of an external electric field unlocks rich nonlinear optical responses. In twisted bilayer Bi$_2$Se$_3$ at the first commensurate angle of 21.78$^\circ$, we find peak shift and injection current conductivities of -14 $ nm.μAV^{-2}$ and 104 $\times 10^8$ $nm.A V^{-2}s^{-1}$, respectively, which lie in the visible spectrum and enable efficient THz applications. The external electric field and point-defect insertion both transform the bilayer into C$_ {3v}$ symmetry, with the selenium vacancy (V$_{Se}$) achieving peak shift and injection current conductivities of -190 nm.$μAV^{-2}$ and -170 $\times 10^8$ $nm.A V^{-2}s^{-1}$. In all three cases, the peak nonlinear optical responses are found to be comparable to those of benchmark 2D materials such as GeS, and the broadband responses, including helicity-dependent current generation, make these engineered bilayers viable candidates for next-generation 2D photovoltaics. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2603_24834 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Engineering Nonlinear Optical Responses via Inversion Symmetry Breaking in Bilayer Bi2Se3 Sharma, Vineet Kumar Okullo, Alana Ghosh, Barun Bansil, Arun Chowdhury, Sugata Materials Science Paucity of naturally occurring noncentrosymmetric materials is stimulating growing interest in engineered two-dimensional systems for nonlinear optical applications. Here, we show that breaking inversion symmetry in centrosymmetric bilayer Bi$_2$Se$_3$ through twisting, point-defect insertion, or the application of an external electric field unlocks rich nonlinear optical responses. In twisted bilayer Bi$_2$Se$_3$ at the first commensurate angle of 21.78$^\circ$, we find peak shift and injection current conductivities of -14 $ nm.μAV^{-2}$ and 104 $\times 10^8$ $nm.A V^{-2}s^{-1}$, respectively, which lie in the visible spectrum and enable efficient THz applications. The external electric field and point-defect insertion both transform the bilayer into C$_ {3v}$ symmetry, with the selenium vacancy (V$_{Se}$) achieving peak shift and injection current conductivities of -190 nm.$μAV^{-2}$ and -170 $\times 10^8$ $nm.A V^{-2}s^{-1}$. In all three cases, the peak nonlinear optical responses are found to be comparable to those of benchmark 2D materials such as GeS, and the broadband responses, including helicity-dependent current generation, make these engineered bilayers viable candidates for next-generation 2D photovoltaics. |
| title | Engineering Nonlinear Optical Responses via Inversion Symmetry Breaking in Bilayer Bi2Se3 |
| topic | Materials Science |
| url | https://arxiv.org/abs/2603.24834 |