Digital light processing 3D printing of ceramics for W-band gradient refractive index metalens

Gradient refractive index (GRIN) metalenses are increasingly valued in high-frequency communication due to their exceptional radiation performance. Ceramics with high dielectric constants and low dielectric losses are ideal candidates for GRIN metalenses. Digital light processing (DLP) 3D printing provides a feasible and efficient approach for manufacturing ceramic GRIN metalenses. However, the scattering of ultraviolet (UV) light by ceramic particles in the slurry reduces the printing accuracy of DLP technology, making it difficult to achieve the intricate structural features required for GRIN metalenses in high-frequency communication. In this work, we propose an approach to improve printing accuracy by optimizing the ceramic slurry composition and implementing a dimensional compensation design strategy. Utilizing geometric optics and the S-parameter inversion method, we design a GRIN metalens consisting of two distinct types of subwavelength unit cells (Y-shaped and circular hole geometries) with a minimum feature size of 160 μm. Through a refined slurry formulation and precise design parameter compensation, high-fidelity ceramic GRIN metalenses are successfully fabricated. The fabricated metalens exhibits a maximum gain enhancement of 18.4 dBi and a deflection angle of ±30° over a bandwidth of 37.84% in the W-band (75-110 GHz). The highly directional far-field beam radiation and efficient beam steering capabilities highlight the potential of ceramic GRIN metalenses for applications in satellite communications, radar systems, and other high-frequency technologies.