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  • Open Access

Continuous far-field zone focusing of flexural waves through phase engineering of metagratings

Zhanrui Tan and Jun Mei*

  • *Contact author: phjunmei@scut.edu.cn
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APS Open Sci. 1, 000081 – Published 3 August, 2026

DOI: https://doi.org/10.1103/k8wt-lybx

Abstract

Continuous far-field zone focusing of flexural wave is highly desirable for applications such as structural health monitoring, energy harvesting, and advanced sensing. In this work, we propose a metalens design paradigm capable of focusing flexural wave across a continuous zone in the far-field region. The metalens is based on an intelligently designed metagrating, in which each unit cell consists of two elliptical holes etched through a thin aluminum plate. Each unit is designed to deflect the incoming waves along a prescribed direction with tunable reflection phase and near-unitary reflection efficiency. The metagrating is engineered such that different unit cells direct the incident wave toward distinct subregions within the target focusing zone. When the reflection phase is uniformly maintained across the metagrating, a continuous extended focusing zone is formed through the superposition of wave beams reflected from all unit cells. This approach achieves a focusing area of approximately 2900λ2 in the far field, with an average intensity enhancement factor of 9.0 and an almost homogeneous intensity distribution. The compact planar architecture of the metalens not only offers a flexible and practical solution for far-field zone focusing, but also holds promise as a versatile planar component suitable for system integration.

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APS Open Sci. 1, 000081– Published 3 August, 2026
Vol. 1
  • Received 5 February 2026
  • Accepted 20 July 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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