Structural color based on a TiO₂ semi-ellipsoidal nanostructures metasurface

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Structural colors offer a pigment-free alternative for coloration.
• Titanium dioxide (TiO2) metasurfaces show promise for color saturation and loss control.
• Single-dielectric metasurfaces often suffer from multipolar modes, reducing color saturation.

Purpose of the Study:

• To design and demonstrate TiO2 semi-ellipsoidal nanostructures to suppress higher-order modes.
• To achieve high color saturation and purity in structural coloration.
• To provide a pathway for advanced structural color display devices.

Main Methods:

• Utilizing all-TiO2 semi-ellipsoidal nanostructures as unit cells in metasurfaces.
• Leveraging continuously varying surface profiles to suppress unwanted modes.
• Fabricating and characterizing the semi-ellipsoidal nanostructures for optical performance.

Main Results:

• The semi-ellipsoidal design effectively suppresses higher-order multipolar modes.
• High reflectance with narrow full-width at half-maximum (FWHM) reflection peaks was achieved.
• A wide color range from blue-green to orange-red was demonstrated without multilayer stacks.

Conclusions:

• Continuously varying surface profiles in nanostructures enhance color purity.
• The proposed metasurface design simplifies fabrication and material deposition.
• This approach enables the development of structural color displays with superior color quality.