Collimated flat-top beam shaper metasurface doublet based on the complex-amplitude constraint Gerchberg–Saxton algorithm

Xue Dongbai; Dun Xiong; Wei Zeyong; Li DongDong; Zhu Jingyuan; Zhang Zhanyi; Wang Zhanshan; Cheng Xinbin

doi:10.1515/nanoph-2023-0719

Nanophotonics (Jan 2024)

Collimated flat-top beam shaper metasurface doublet based on the complex-amplitude constraint Gerchberg–Saxton algorithm

Xue Dongbai,
Dun Xiong,
Wei Zeyong,
Li DongDong,
Zhu Jingyuan,
Zhang Zhanyi,
Wang Zhanshan,
Cheng Xinbin

Affiliations

Xue Dongbai: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China
Dun Xiong: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China
Wei Zeyong: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China
Li DongDong: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China
Zhu Jingyuan: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China
Zhang Zhanyi: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China
Wang Zhanshan: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China
Cheng Xinbin: Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai200092, China

DOI: https://doi.org/10.1515/nanoph-2023-0719
Journal volume & issue: Vol. 13, no. 8
pp. 1379 – 1385

Abstract

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Collimated flat-top beam shapers primarily consisting of freeform lenses have a wide range of applications and pose challenges in terms of processing and integration when the diameter is less than millimeters. Metasurfaces represent a promising solution to planarize optics, can mimic any surface curvature without additional fabrication difficulty, and are suitable for flat-top optics. The conventional metasurface design approach relies on imparting the required phase using meta-atoms and encounters challenges in amplitude modulation due to near-field coupling and varying transmittances among meta-atoms with different phases, making the design of flat-top beam shapers difficult. In this paper, we propose a complex-amplitude constraint Gerchberg–Saxton algorithm for designing a collimated flat-top beam shaper metasurface doublet, which avoids the influence of strong near-field coupling on the amplitude distribution and simultaneously considers the amplitude-phase characteristics of the meta-atoms. A collimated flat-top beam with exceptional homogeneity U p of approximately 0.01, a wavefront error less than 0.1λ, and a transmittance higher than 86 % is experimentally obtained, comparable to commercial products based on freeform lenses. A collimated flat-top beam shaper metasurface doublet for generating flat-top beam is introduced, promoting efficient integration with laser systems.

Published in Nanophotonics

ISSN: 2192-8606 (Print); 2192-8614 (Online)
Publisher: De Gruyter
Country of publisher: Germany
LCC subjects: Science: Physics
Website: https://www.degruyter.com/journal/key/nanoph/html#submit

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