Dual-layer achromatic metalens design with an effective Abbe number

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Planar achromatic metalenses offer potential for ultra-compact optical devices.
• Single-layer achromatic metalenses require complex meta-atoms for dispersion compensation.

Purpose of the Study:

• To design a dual-layer achromatic metalens with simplified components.
• To compensate for chromatic dispersion using stacked meta-lenses.
• To demonstrate a practical design for wide-bandwidth achromatic focusing.

Main Methods:

• Introduced an effective Abbe number for metalens design.
• Utilized lens maker equations for a dual-layer configuration.
• Employed high refractive index dielectric cylindrical meta-atoms with varying radii.

Main Results:

• Achieved a dual-layer achromatic metalens with minimal focal length difference across the visible spectrum.
• Demonstrated an average focusing efficiency exceeding 50%.
• Simplified design and fabrication processes compared to single-layer counterparts.

Conclusions:

• The proposed dual-layer metalens design is effective for achromatic focusing.
• The method simplifies fabrication, making it suitable for multi-functional flat optical devices.
• This approach shows promise for advanced compact optical system development.