Chiral plasmonic surfaces, featuring nanohelicoidal structures, exhibit significant optical rotation but are typically fabricated using complex, multi-step processes that are costly and substrate-specific. Additionally, creating large-scale photonic patterns on flexible, polymeric substrates has been a challenge. In this study, we introduce a substrate-tolerant, direct-write patterning technique to fabricate silver nanohelicoids with variable optical activity using circularly polarized light (CPL). This method enables the production of centimeter-scale chiral plasmonic surfaces in minutes, using affordable medium-power lasers. The formation of nanohelicoids results from symmetry-broken site-selective deposition and self-assembly of silver nanoparticles. By adjusting the ellipticity and wavelength of the incident photons, we can dynamically control the handedness and size of the silver nanohelicoids, allowing real-time modulation of chirality during printing. This technique enables the creation of complex, multifunctional metasurfaces with high polarization rotation and fine spatial resolution. Our computer-driven direct-write system can print local patterns with varying optical activities across distances spanning four orders of magnitude. Notably, this CPL-based printing does not require organic ligands, offering a promising approach for chiroptical diagnostics by enhancing sensitivity to the dielectric environment and eliminating the charge transport issues seen with solution-processed nanomaterials. Spectroscopic analysis of chiral analytes, such as pepsin and L- and D-lysine, showed significant wavelength shifts in CD spectra, with a detection limit below 100 pM. This method provides a rapid, cost-effective approach to developing chiral plasmonic surfaces, advancing chiral photonics for applications in health and information technologies.
