Ultrafast Laser‐Induced Plasmonic Modulation of Optical Properties of Dielectrics at High Resolution

Abstract The size‐ and shape‐dependent localized surface plasmon properties of metallic nanoparticles (NPs) enable nanoscale‐enhanced near‐field applications in a wide range of fields, including spectroscopy, nonlinear optics, and sensing. Orderly assembled NPs can construct plasmonic metamaterials for light manipulation at a subwavelength scale, exhibiting new collective properties in resonant modes regulated by plasmon coupling between their fundamental components. Despite the recognition of its significant advantages in photonics integration, plasmonic‐based tailored optical responses for practical applications have remained elusive due to limitations in scaling up processes, as neither etching nor assembly can design and fabricate embedded plasmonic devices into functional devices/structures. Here, the assembly of plasmonic NPs is demonstrated by ultrafast laser‐induced writing‐on‐demand inside solids, tailoring their distribution and sizes. By controlling the laser scanning speed, the in situ redistribution of NPs is observed. Plasmon mediated local energy deposition is considered as the main mechanism driving nano‐patterning at a subwavelength range. A direct nano‐printing is realized by utilizing the resonant optical response of laser‐modified NP structures/patterns. This work paves the way for directly induced NP composite structures inside transparent materials at a well‐defined and controlled depth for plasmonic applications.