Wideband and high-efficiency spin-locked achromatic meta-device

Area of Science:

• Electromagnetics and Metamaterials
• Wave Optics and Photonics
• Microwave Engineering

Background:

• Achromatic devices are crucial for wave manipulation in imaging and communication but suffer from narrow bandwidth, low efficiency, and large sizes.
• Existing achromatic technologies face significant limitations hindering their practical application.
• Metasurfaces offer a promising platform for miniaturized and efficient wave control devices.

Purpose of the Study:

• To propose a general strategy for designing spin-locked achromatic metasurfaces with broadband and high efficiency in the microwave region.
• To overcome the limitations of conventional achromatic devices.
• To demonstrate the practical application of these metasurfaces in real-world devices.

Main Methods:

• A multi-resonant model was employed to precisely control dispersion over a wide bandwidth by adjusting resonant intensity, number, and frequency.
• The design strategy focused on achieving spin-locked achromatic properties.
• Experimental validation of two ultra-thin achromatic meta-devices: a deflector and a lens.

Main Results:

• An achromatic deflector successfully reflected normal incident waves to a constant angle between 9.5 and 11.5 GHz.
• An achromatic lens achieved focusing of excitations at identical focal points.
• Experimental efficiencies ranged from 71-82% for the deflector and 57-65% for the lens within the operational bandwidth, with preserved polarization.
• The meta-devices exhibited ultra-thin profiles.

Conclusions:

• The proposed strategy enables the design of broadband, high-efficiency achromatic metasurfaces.
• These meta-devices offer significant advancements over existing technologies and can be adapted for other frequency ranges.
• The research inspires the development of ultrabroadband and high-efficiency metadevices for future applications.