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| Main Authors: | , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2510.23592 |
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| _version_ | 1866914296031608832 |
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| author | He, Zhiping Fang, Xu Hu, Juejun |
| author_facet | He, Zhiping Fang, Xu Hu, Juejun |
| contents | Tunable active metasurfaces have become a major research focus in recent years. Among tuning mechanisms, all-optical coherent control stands out because it requires no material or geometric change, enabling ultrafast, low-energy, interference-based modulation of amplitude, phase, and polarization in ultrathin devices. However, when applied to phase-gradient metasurfaces, coherent control has been limited to small apertures effectively confined to a single Fresnel zone, leading to large divergence and degraded beam quality. Here we propose and numerically validate a scalable method that enables large-area coherent control. The key idea is to use coherent illumination to tune the phase gradient within each Fresnel zone while a direct search algorithm optimizes zone-by-zone parameters to meet system-level targets. Using this principle, we demonstrate continuous tuning of a large-area metasurface for continuous beam-steering without per-meta-atom phase actuation. The same framework applies broadly to continuously tunable phase-gradient optics, including varifocal metalenses, parfocal zoom metalenses, tunable axicons, and related dynamic focusing elements. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_23592 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Coherent all-optical tuning of large-area phase-gradient metasurface He, Zhiping Fang, Xu Hu, Juejun Optics Tunable active metasurfaces have become a major research focus in recent years. Among tuning mechanisms, all-optical coherent control stands out because it requires no material or geometric change, enabling ultrafast, low-energy, interference-based modulation of amplitude, phase, and polarization in ultrathin devices. However, when applied to phase-gradient metasurfaces, coherent control has been limited to small apertures effectively confined to a single Fresnel zone, leading to large divergence and degraded beam quality. Here we propose and numerically validate a scalable method that enables large-area coherent control. The key idea is to use coherent illumination to tune the phase gradient within each Fresnel zone while a direct search algorithm optimizes zone-by-zone parameters to meet system-level targets. Using this principle, we demonstrate continuous tuning of a large-area metasurface for continuous beam-steering without per-meta-atom phase actuation. The same framework applies broadly to continuously tunable phase-gradient optics, including varifocal metalenses, parfocal zoom metalenses, tunable axicons, and related dynamic focusing elements. |
| title | Coherent all-optical tuning of large-area phase-gradient metasurface |
| topic | Optics |
| url | https://arxiv.org/abs/2510.23592 |