Silica Nanoparticle-Based Photoresin for THz High-Resolution 3-D Microfabrication by Two-Photon Polymerization

Two-photon polymerization is a promising fabrication technique for complex 3-D structures operating at terahertz (THz) given its sub-
$\mu$
m resolution with hundreds of mm
$^{3}$
print volume capability. However, standard photoresins exhibit unsuitably high THz absorption and have poor mechanical, chemical, and thermal stability. To address the latter three issues, a new photoresin (commercially known as GP-Silica) based on silica nanoparticles dispersed in a photocurable binder matrix has been recently developed. To assess its suitability for THz devices, we report the THz dielectric properties of GP-Silica and compare them with standard 3-D printable materials. We find that GP-Silica outperforms the other photoresins by almost five times in terms of absorption, which finally unlocks additive manufacturing for THz applications.