From Beam Steering to Strong Absorption: Tailorable Dielectric Composites for Terahertz Metasurfaces

Dielectric properties of constituent materials fundamentally determine the functionality of dielectric metasurfaces, governing phase modulation, resonance and absorption. Yet in the terahertz regime, dielectric metasurfaces remain largely restricted to deep‐reactive‐ion‐etched silicon, limiting material's tunability, conformability and scalability. Here we present a composite‐based, high‐precision templating strategy for scalable 3D terahertz dielectric metasurfaces with tailorable electromagnetic response. By varying fillers within a common polymer matrix, we tune the dielectric properties from a high‐index, low‐loss regime to a low‐index, high‐loss regime, enabling material platform to support functionalities ranging from beam steering to broadband absorption. Utilizing a scalable soft‐lithography approach, we achieve the high‐fidelity fabrication of through‐hole metasurfaces that feature full 2π phase modulation at 340 GHz and robust broadband absorption exceeding 94% across the 0.1–1.1 THz range. Furthermore, these devices demonstrate exceptional chemical stability. This work establishes dielectric property engineering for composites as a scalable route to customizable terahertz metasurfaces.