Surface Lattice Resonances (SLRs) found in uniform plasmonic metasurfaces feature high Q-factors, enabling applications in sensing and nanolasing. To scale up their production, we introduce the Capillary-force-Assisted Particle Assembly method (CAPA). It allows to assemble colloidal nanoparticles onto patterned templates. We demonstrate large hexagonal and square lattices comprised of single-crystal Ag nanoparticles with high quality SLRs. They can be excited into optomechanical oscillations which modulate the LSPR and in turn the SLR over time, giving the metasurface intriguing properties in the ultrafast regime. Moreover, we tailored the SLR to match the excitation wavelength used in Raman spectroscopy. This allowed to create SERS substrates with improved performance, achieving 100 times higher sensitivity at the target wavelength. Finally, we interfaced plasmonic metasurfaces with gain media and registered room temperature nanolasing. The demonstrated applications showcase the versatility of CAPA and we expect self-assembly to play a major role in the development of large scale metasurfaces and nanophotonics devices.
The ability to precisely manipulate nanoscale objects and form defined assemblies with extraordinary optical properties has been attracting researchers’ interest for decades. Top-down lithography approaches were the first choice to define sub-wavelength patterns of metasurfaces. Recently, template-based self-assembly methods emerged allowing to deposit chemically synthesized nanoparticle (NP) colloids into tailored traps. Clean-room lithography techniques are required only once—to produce the template master, which can be replicated in an elastomer and used as the NP deposition template. The capillary force deposition ensured nearly 100% yield of tailored single or multi-particle assemblies over cm scales. When the pitch between scattering NPs overlaps the localized surface plasmon band, a high-quality surface lattice resonance (SLR) emerges. We have demonstrated that the SLR can couple to the NP optomechanical oscillations or can be exploited for sensing and nanolasing applications.
In this paper, we propose a systematic approach to controllably fabricate silver nanoparticles, dendrites and nanovoids on porous template based on silicon and two-step wet process. Geometry of metallic structures was managed by variation of dopant type of silicon, regimes of template formation and deposition of silver. General models of each structure were developed and studied for distribution and strength of electric field arising in them under 473, 633 and 785 nm lasers. Simulation results revealed reasons of variable activity of fabricated structures in surface enhanced Raman spectroscopy, which allowed to define optimal conditions of analysis of target molecules.
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