Strong interlayer coupling and chiral flat-band cascades in twisted bilayer gratings
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arXiv
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| Autori principali: | , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866908583396900864 |
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| author | Choi, Daegwang Lee, Soon-Jae Cho, Seung-Woon Bark, Chan Bin Pak, Seik Shin, Dong-Jin Park, Moon Jip Gong, Su-Hyun |
| author_facet | Choi, Daegwang Lee, Soon-Jae Cho, Seung-Woon Bark, Chan Bin Pak, Seik Shin, Dong-Jin Park, Moon Jip Gong, Su-Hyun |
| contents | From atomic crystals to macroscopic material structures, twisted bilayer systems have emerged as a promising route to control wave phenomena. In few-layer van der Waals (vdW) materials, however, the intrinsically weak interlayer coupling typically demands fine control of small twist angles to reach magic-angle conditions. Here, we show that one-dimensional photonic crystal bilayers can overcome this limitation by accessing a regime of strong interlayer coupling -- comparable to intralayer coupling. This strong coupling enables flat-band formation over a broad angular range even at large twist angles. We experimentally realize this regime by stacking WS$_2$ gratings using a two-step lithography method, resulting in ultra-wide chiral flat-band cascades in magic-angle twisted bilayer gratings. Our work not only provides a platform for designing photonic applications with tunable localization but also explores a new regime of physics unattainable in conventional solid-state based moiré systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_07381 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Strong interlayer coupling and chiral flat-band cascades in twisted bilayer gratings Choi, Daegwang Lee, Soon-Jae Cho, Seung-Woon Bark, Chan Bin Pak, Seik Shin, Dong-Jin Park, Moon Jip Gong, Su-Hyun Optics Mesoscale and Nanoscale Physics From atomic crystals to macroscopic material structures, twisted bilayer systems have emerged as a promising route to control wave phenomena. In few-layer van der Waals (vdW) materials, however, the intrinsically weak interlayer coupling typically demands fine control of small twist angles to reach magic-angle conditions. Here, we show that one-dimensional photonic crystal bilayers can overcome this limitation by accessing a regime of strong interlayer coupling -- comparable to intralayer coupling. This strong coupling enables flat-band formation over a broad angular range even at large twist angles. We experimentally realize this regime by stacking WS$_2$ gratings using a two-step lithography method, resulting in ultra-wide chiral flat-band cascades in magic-angle twisted bilayer gratings. Our work not only provides a platform for designing photonic applications with tunable localization but also explores a new regime of physics unattainable in conventional solid-state based moiré systems. |
| title | Strong interlayer coupling and chiral flat-band cascades in twisted bilayer gratings |
| topic | Optics Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2510.07381 |