Layer-by-Layer Assembly of Heterogeneous Modular Nanocomposites

Layer-by-layer (LbL) assembly of nanoparticles and polyelectrolyte multilayers into alternating nonrepetitive strata (modules) demonstrates an important advance in heterogeneous nanocomposites from random or repetitive distributions of nanoparticles to a versatile modular design. The morphology and composition for each module are determined by the LbL assembly conditions, as confirmed by cross-section transmission electron microscopy (TEM) and by X-ray photoelectron spectroscopy (XPS). Thickness and spacing of the modules are maintained in the 5–50 nm range relevant for nanoscale proximal interactions

Low-Loss, Extreme Subdiffraction Photon Confinement via Silicon Carbide Localized Surface Phonon Polariton Resonators

Plasmonics provides great promise for nanophotonic applications. However, the high optical losses inherent in metal-based plasmonic systems have limited progress. Thus, it is critical to identify alternative low-loss materials. One alternative is polar dielectrics that support surface phonon polariton (SPhP) modes, where the confinement of infrared light is aided by optical phonons. Using fabricated 6H-silicon carbide nanopillar antenna arrays, we report on the observation of subdiffraction, localized SPhP resonances. They exhibit a dipolar resonance transverse to the nanopillar axis and a monopolar resonance associated with the longitudinal axis dependent upon the SiC substrate. Both exhibit exceptionally narrow linewidths (7–24 cm^–1), with quality factors of 40–135, which exceed the theoretical limit of plasmonic systems, with extreme subwavelength confinement of (λ_res³/<i>V</i>_eff)^1/3 = 50–200. Under certain conditions, the modes are Raman-active, enabling their study in the visible spectral range. These observations promise to reinvigorate research in SPhP phenomena and their use for nanophotonic applications