Open AccessPlasmonic-induced self-assembly of WGM cavities via laser cavitation
Author(s) -
Rodrigo Sato,
Joel Henzie,
Satoshi Ishii,
Ken Takazawa,
Yoshihiko Takeda
Publication year - 2020
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.401662
Subject(s) - lasing threshold , whispering gallery wave , materials science , plasmon , optics , refractive index , laser , optoelectronics , plasmonic nanoparticles , free spectral range , resonator , photoexcitation , surface plasmon resonance , wavelength , nanoparticle , nanotechnology , excitation , physics , quantum mechanics
We show how photoexcitation of a single plasmonic nanoparticle (NP) in solution can create a whispering-gallery-mode (WGM) droplet resonator. Small nano/microbubbles are initially formed by laser-induced heating that is localized by the plasmon resonance. Fast imaging shows that the bubbles collect and condense around the NP and form a droplet in the interior of the bubble. Droplets containing dye generated lasing modes with wavelengths that depend on the size of the droplet, refractive index of the solvent, and surrounding environment, matching the behavior of a WGM. We demonstrated this phenomenon with two kinds of Au NPs in addition to TiN NPs and observed cavity diameters as small as 4.8 µm with a free spectral range (FSR) of 12 nm. These results indicate that optical pumping of plasmonic NPs in a gain medium can generate lasing modes that are not directly associated with the plasmon cavity but can arise from its photophysical processes. This process may serve as a method to generate plasmonic/photonic optical microcavities in solution on demand at any location in a solvent using free-space coupling in/out of the cavity.