Nearly arbitrary terahertz metamaterials by conformal metallization on multi-photon lithography

Area of Science:

• Condensed Matter Physics and Materials Science
• Electromagnetism and Photonics
• Nanotechnology

Background:

• The 5G/6G terahertz (THz) era necessitates advanced metamaterials with integrated functions and complex geometries.
• Current 2D lithography methods struggle to fabricate the high-complexity, geometry-scalable THz architectures required.
• Existing in-plane, film-like metamaterials are insufficient for next-generation THz demands.

Purpose of the Study:

• To propose a novel conformal metallization strategy for fabricating high-dimensional THz metamaterials.
• To overcome the limitations of 2D lithography for complex THz architectures.
• To enable the development of next-generation THz metamaterials with enhanced functionality and design freedom.

Main Methods:

• Utilized 3D multi-photon lithography to create nanometric topologies.
• Employed a stepwise ion-sputtering technique with metal or semimetal for conformal metallization.
• Demonstrated the fabrication of chiral meta-atoms, hollow/arbitrary meta-structures, and bound states in the continuum (BIC) metasensors.

Main Results:

• Successfully fabricated 3D THz metamaterials with nanometric precision and high conductivity.
• Achieved programmable THz functions, unit-cell precision, and resonant properties without geometric constraints.
• Demonstrated the versatility of the method for creating diverse metamaterial structures, including chiral and BIC-based designs.

Conclusions:

• The proposed conformal metallization strategy effectively enables the fabrication of complex, high-dimensional 3D THz metamaterials.
• This approach significantly extends the functional capabilities of THz metamaterials into the third dimension.
• The developed 3D THz metamaterials satisfy the stringent requirements for next-generation THz technologies.