Affiliation:
1. Nankai University
2. Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology
3. Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology
Abstract
The powerful wavefront manipulation capability of metasurfaces originates from their subwavelength or deep subwavelength elements with designable optical responses, especially phase responses. However, they usually suffer from performance degradation as the spatial phase gradient is large. To solve this issue, we propose an accurate and efficient nonlocal diffraction engineering mechanism to tailor an arbitrary large-gradient wavefront utilizing superwavelength-scale elements. The fast-varying phase profile is cut into segments according to
2
π
zones rather than subwavelength discretization. Each phase segment is accurately implemented by precisely tailoring the diffraction pattern of the element, where diffraction angles, efficiencies, and phases are controlled simultaneously. As proof of the concept, high numerical aperture cylindrical metalenses are designed using this method and experimentally validated at the terahertz band. The cylindrical metalens is further extended to a full-space metalens, which enables high-quality subwavelength imaging with resolved details of
0.65
λ
. The proposed mechanism offers an efficient way to capture the fast-varying wavefront using relatively coarse geometries with new physical insights.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China
Subject
Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials
Cited by
9 articles.
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