Laser‐Directed Asymmetric Growth of Plasmonic Chiral Ensembles

Abstract

AbstractChiral plasmonic system due to its enhanced chiroptic activity in the visible region has attracted numerous interests in the last decade. Although various strategies have been developed for the fabrication of chiral plasmonic nanostructures, the limitations of cost‐effectiveness and controllability have been the main obstacle for their practical applications. Here, continuous wave laser is used to direct the growth of chiral ensembles of gold nanoparticles (AuNPs). These AuNPs are grown from the Au‐doped titanium dioxide (TiO2) films in a ring‐shaped arrangement under photoreduction, which can then evolve into nanotetramers, nanotrimers, and nanodimers at different irradiation time, showing good controllability and reproducibility. Especially, the nanodimers and nanotrimers show circular differential scattering (CDS) over 20%. The optical chirality of the nanotrimers presents a prominent superchiral field, which is demonstrated for the optical sensing of chiral molecules (approximately × 10−3 m) with large spectral dissymmetric factors. Such an unprecedented growth strategy via laser direct writing is facile, tailorable, location‐selective, and ligand‐free, which presents significant implications for on‐chip integration of chiral nano‐optic devices and surface‐enhanced Raman optical activity (SEROA).