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Multifrequency achromatic metalens realizing acoustic multi-point focusing.

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Title: Multifrequency achromatic metalens realizing acoustic multi-point focusing.
Authors: Yao, Jie1 (AUTHOR) yaojie1@njnu.edu.cn, Chen, Xing1 (AUTHOR), Dong, Shu-Ming1 (AUTHOR), Zhu, Xing-Feng1,2 (AUTHOR), Wu, Da-Jian1,2 (AUTHOR) wudajian@njnu.edu.cn
Source: Journal of the Acoustical Society of America. May2026, Vol. 159 Issue 5, p4459-4465. 7p.
Subjects: Phase modulation, Acoustic resonators
Abstract: Up to now, achromatic focusing techniques have focused on the design and improvement of single-point focusing, neglecting the wide application possibilities of multi-point focusing. Here, we propose a multifrequency achromatic metalens to achieve multiple focal points based on complex-amplitude coding. The complex-valued wavefront-shaping function is decomposed into two independent phase distributions, which are coded into the metalens through subwavelength units. The phase dispersion for multi-point focusing can be achieved in this way. Theoretical analyses predict that different coding sequences have little influence on the focal pattern, implying extra freedom in designing the metalens. Limited by available meta-atoms, achromatic multi-point focusing has been realized only at discrete frequencies in this study. By adjusting the coding carefully, a triple-frequency achromatic metalens has been constructed through space curved structures. Three achromatic focal points have been demonstrated through experiments at 3.5, 4, and 5 kHz. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Up to now, achromatic focusing techniques have focused on the design and improvement of single-point focusing, neglecting the wide application possibilities of multi-point focusing. Here, we propose a multifrequency achromatic metalens to achieve multiple focal points based on complex-amplitude coding. The complex-valued wavefront-shaping function is decomposed into two independent phase distributions, which are coded into the metalens through subwavelength units. The phase dispersion for multi-point focusing can be achieved in this way. Theoretical analyses predict that different coding sequences have little influence on the focal pattern, implying extra freedom in designing the metalens. Limited by available meta-atoms, achromatic multi-point focusing has been realized only at discrete frequencies in this study. By adjusting the coding carefully, a triple-frequency achromatic metalens has been constructed through space curved structures. Three achromatic focal points have been demonstrated through experiments at 3.5, 4, and 5 kHz. [ABSTRACT FROM AUTHOR]
ISSN:00014966
DOI:10.1121/10.0043924