Micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design
Abstract In order to focus light at a desired depth, wavefront shaping of the incident light is required. Light focusing is used in applications such as medical imaging, sensing, power dividers, etc. For this purpose, various phase plates can be exploited, but we propose a periodic phase plate. The...
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Nature Portfolio
2025-08-01
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| Online Access: | https://doi.org/10.1038/s41598-025-15805-z |
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| author | Morteza Khoshhal Mahmoud Shahabadi |
| author_facet | Morteza Khoshhal Mahmoud Shahabadi |
| author_sort | Morteza Khoshhal |
| collection | DOAJ |
| description | Abstract In order to focus light at a desired depth, wavefront shaping of the incident light is required. Light focusing is used in applications such as medical imaging, sensing, power dividers, etc. For this purpose, various phase plates can be exploited, but we propose a periodic phase plate. The reason for considering periodic structures is to profit from wavefront shaping of several periods to focus light at larger depths, which can be a challenging task without a periodic phase plate. Using this method, the focus quality is such that its Full Width at Half Maximum (FWHM) reaches in the order of the diffraction limit, while maximizing power concentration. We also assume that the phase plate elements are of micron-scale, so that it does not require nanofabrication. The modelling and analysis method used in this paper accurately takes the coupling among adjacent phase plate elements into account, i.e., it does not rely on local phase approximation. Since the introduced phase plate has a periodic structure, the focusing is repeated periodically, which finds several applications. Using our computational technique, one is able to rigorously analyze and design phase plates as wide as $$1200 \lambda _o$$ . In a sample design, we show that $$96.89\%$$ of the illuminated power reaches a depth of $$750000 \lambda _o$$ or 1m at a wavelength of $$1.33\mu m$$ . Approximately $$25\%$$ of the incident power is focused within only $$1\%$$ of the unit cell width. Moreover, despite large depth of focusing, its FWHM is in the order of the diffraction limit. In this paper, in addition to achieving light focusing at larger depths, we also demonstrate that the proposed methodology can be utilized for focusing with a FWHM close to the diffraction limit down to $$0.54 \lambda _o$$ , double focusing, and focusing with a high Numerical Aperture (NA) of 0.97. |
| format | Article |
| id | doaj-art-e3989f7e57ea4b79b8aa940be5329c6b |
| institution | Kabale University |
| issn | 2045-2322 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Nature Portfolio |
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| series | Scientific Reports |
| spelling | doaj-art-e3989f7e57ea4b79b8aa940be5329c6b2025-08-24T11:21:50ZengNature PortfolioScientific Reports2045-23222025-08-0115111610.1038/s41598-025-15805-zMicron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and designMorteza Khoshhal0Mahmoud Shahabadi1Photonics Research Laboratory, Center of Excellence on Applied Electromagnetic Systems, School of Electrical and Computer Engineering, College of Engineering, University of TehranPhotonics Research Laboratory, Center of Excellence on Applied Electromagnetic Systems, School of Electrical and Computer Engineering, College of Engineering, University of TehranAbstract In order to focus light at a desired depth, wavefront shaping of the incident light is required. Light focusing is used in applications such as medical imaging, sensing, power dividers, etc. For this purpose, various phase plates can be exploited, but we propose a periodic phase plate. The reason for considering periodic structures is to profit from wavefront shaping of several periods to focus light at larger depths, which can be a challenging task without a periodic phase plate. Using this method, the focus quality is such that its Full Width at Half Maximum (FWHM) reaches in the order of the diffraction limit, while maximizing power concentration. We also assume that the phase plate elements are of micron-scale, so that it does not require nanofabrication. The modelling and analysis method used in this paper accurately takes the coupling among adjacent phase plate elements into account, i.e., it does not rely on local phase approximation. Since the introduced phase plate has a periodic structure, the focusing is repeated periodically, which finds several applications. Using our computational technique, one is able to rigorously analyze and design phase plates as wide as $$1200 \lambda _o$$ . In a sample design, we show that $$96.89\%$$ of the illuminated power reaches a depth of $$750000 \lambda _o$$ or 1m at a wavelength of $$1.33\mu m$$ . Approximately $$25\%$$ of the incident power is focused within only $$1\%$$ of the unit cell width. Moreover, despite large depth of focusing, its FWHM is in the order of the diffraction limit. In this paper, in addition to achieving light focusing at larger depths, we also demonstrate that the proposed methodology can be utilized for focusing with a FWHM close to the diffraction limit down to $$0.54 \lambda _o$$ , double focusing, and focusing with a high Numerical Aperture (NA) of 0.97.https://doi.org/10.1038/s41598-025-15805-z |
| spellingShingle | Morteza Khoshhal Mahmoud Shahabadi Micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design Scientific Reports |
| title | Micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design |
| title_full | Micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design |
| title_fullStr | Micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design |
| title_full_unstemmed | Micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design |
| title_short | Micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design |
| title_sort | micron scale binary periodic phase plate for increased depth of focusing based on a non local analysis and design |
| url | https://doi.org/10.1038/s41598-025-15805-z |
| work_keys_str_mv | AT mortezakhoshhal micronscalebinaryperiodicphaseplateforincreaseddepthoffocusingbasedonanonlocalanalysisanddesign AT mahmoudshahabadi micronscalebinaryperiodicphaseplateforincreaseddepthoffocusingbasedonanonlocalanalysisanddesign |