Direct Printing of Helical Metal Arrays by Circularly Polarized Light

Chiral metasurface with orthogonal nanohelical metal arrays provide strong optical rotation but demands multi-step nanofabrication at low-pressure and/or high-temperature conditions, which is incompatible with many substrates and high-throughput assessment. Submillimeter local photonic patterns with various optical polarization were also hitherto unattainable over the same substrate. Here, we demonstrate direct substrate-tolerant printing of silver nanohelicoids with a locally variable optical activity using circularly polarized light (CPL), producing centimeter-scale chiral metasurface within minutes. The light-illuminated sites on the substrate immersed in an aqueous silver ion solution are activated for heterogeneous nucleation at room temperature. Subsequent CPL-induced asymmetric site-selective deposition and self-assembly of the silver nanoparticles (NPs) sculpt the orthogonal silver helicoids at the interface as one-pot synthesis. The ellipticity and wavelength of the incident photons control the handedness and size of the printed silver helicoids, realizing on-the-fly modulation of optical polarization while printing local patterns. Processing simplicity, high polarization rotation, and fine spatial resolution of the light-driven printing can provide a pathway to the sustainable production of chiral plasmonic metasurfaces, accelerating the development of chiral photonics for health and information technologies.