UC San Diego

Localized surface plasmon resonance (LSPR) is a collective oscillation of electrons at the interface of metallic nanostructures or metal-dielectric interface. At the resonance frequency, light-matter interaction results in a coherent coupling between surface conduction electrons and incident light, generating an enhanced electromagnetic (EM) field at the plasmonic nanostructure surface. Taking advantage of this EM field enhancement, plasmonic nanostructures have been widely used in nonlinear optics, chemical sensing, biomedical imaging, and photocatalysis. However, due to the requirement for precisely controlled size, shape, and orientation, most of these plasmonic nanostructures have been fabricated with top-down methods; the major challenge has been industrial-scale production of plasmonic devices.In this work, I have developed a four-step bottom-up total fabrication process for cost-effective and wafer-scale fabrication of plasmonic platforms. First, we used wet chemistry methods to synthesize (1) plasmonic noble metal nanocrystals with a tunable size and shape, and (2) plasmonic semiconductor nanocrystals with a tunable composition, resonance frequency, and bandgap. Next, we used self-assembly methods to group multiple plasmonic components together and build a submicron-scale meta-atom. Owing to nanometer-scale separation between plasmonic components, there was a strong plasmon coupling effect within the artificial building blocks of metasurface (named as meta-atoms) that resulted in two orders of magnitude in near-field enhancement. Then we used a micro-fabrication method, such as Langmuir-Blodgett film, a soft imprint, etc., to build a wafer-scale plasmonic device that consists of billions of repeating meta-atoms. Finally, we used surface chemistry to functionalize the surface of plasmonic devices and then used these plasmonic devices for different applications, including optical second harmonic generation, water pollutant molecules sensing, and wafer-scale 2D materials characterization.