Broadband achromatic wavefront tailoring with high-efficiency reflective metadevices.

Area of Science:

• Electromagnetics
• Materials Science
• Wave Optics

Background:

• Metasurfaces offer advanced control over electromagnetic (EM) waves but often suffer from frequency dispersion, limiting performance.
• Achromatic metasurfaces are well-studied at optical frequencies, but microwave counterparts with reduced thickness remain a challenge.

Purpose of the Study:

• To propose a generic scheme for designing achromatic metasurfaces in the microwave domain.
• To overcome limitations of existing microwave metasurfaces, particularly their thickness and frequency dispersion.

Main Methods:

• Designing high-efficiency meta-atoms with tailored reflection phases from resonant and geometric origins.
• Developing a strategy for broadband control of EM far-field wavefronts.
• Fabricating and experimentally validating three achromatic metadevices.

Main Results:

• Demonstrated achromatic metasurfaces capable of controlling EM wavefronts across a microwave broadband (8-10 GHz).
• Successfully realized anomalous reflection, focusing, and Bessel beam generation with the fabricated metadevices.
• Achieved high performance without significant thickness increase.

Conclusions:

• The proposed scheme enables the design of high-performance achromatic metasurfaces in low-frequency domains.
• This advancement opens possibilities for improved microwave imaging, radar detection, and wireless communication systems.