3 research outputs found
Single-Crystalline Aluminum Nanostructures on a Semiconducting GaAs Substrate for Ultraviolet to Near-Infrared Plasmonics
Aluminum, as a metallic material for plasmonics, is of great interest because it extends the applications of surface plasmon resonance into the ultraviolet (UV) region and is superior to noble metals in natural abundance, cost, and compatibility with modern semiconductor fabrication processes. Ultrasmooth single-crystalline metallic films are beneficial for the fabrication of high-definition plasmonic nanostructures, especially complex integrated nanocircuits. The absence of surface corrugation and crystal boundaries also guarantees superior optical properties and applications in nanolasers. Here, we present UV to near-infrared plasmonic resonance of single-crystalline aluminum nanoslits and nanoholes. The high-definition nanostructures are fabricated with focused ion-beam milling into an ultrasmooth single-crystalline aluminum film grown on a semiconducting GaAs substrate with a molecular beam epitaxy method. The single-crystalline aluminum film shows improved reflectivity and reduced two-photon photoluminescence (TPPL) due to the ultrasmooth surface. Both linear scattering and nonlinear TPPL are studied in detail. The nanoslit arrays show clear Fano-like resonance, and the nanoholes are found to support both photonic modes and localized surface plasmon resonance. We also found that TPPL generation is more efficient when the excitation polarization is parallel rather than perpendicular to the edge of the aluminum film. Such a counterintuitive phenomenon is attributed to the high refractive index of the GaAs substrate. We show that the polarization of TPPL from aluminum preserves the excitation polarization and is independent of the crystal orientation of the film or substrate. Our study gains insight into the optical property of aluminum nanostructures on a high-index semiconducting GaAs substrate and illustrates a practical route to implement plasmonic devices onto semiconductors for future hybrid nanodevices
High-Performance Plasmonic Nanolasers with a Nanotrench Defect Cavity for Sensing Applications
Recent developments
in small footprint plasmonic nanolasers show
promise for active optical sensing with potential applications in
various fields, including real-time and label-free biochemical sensing,
and gas detection. In this study, we demonstrate a novel hybrid plasmonic
crystal nanolaser that features a ZnO nanowire placed on Al grating
surfaces with a nanotrench defect nanocavity. The lasing action of
gain-assisted defect nanocavity overcomes the ohmic loss parasitically
in the plasmonic nanostructures. Therefore, the plasmonic nanolaser
exhibits an extremely small mode volume, a narrow linewidth Δλ,
and a high Purcell factor that can facilitate the strong interaction
between light and matter. This can be used as a refractive index sensor
and is highly sensitive to local changes in the refractive indices
of ambient materials. By careful design, the near-ultraviolet nanolaser
sensors have significant sensing performances of glucose solutions,
revealing a high sensitivity of 249 nm/RIU and high resolution, with
a figure of merit of 1132, at the resonant wavelength of 373 nm
High-Operation-Temperature Plasmonic Nanolasers on Single-Crystalline Aluminum
The recent development of plasmonics
has overcome the optical diffraction limit and fostered the development
of several important components including nanolasers, low-operation-power
modulators, and high-speed detectors. In particular, the advent of
surface-plasmon-polariton (SPP) nanolasers has enabled the development
of coherent emitters approaching the nanoscale. SPP nanolasers widely
adopted metal–insulator–semiconductor structures because
the presence of an insulator can prevent large metal loss. However,
the insulator is not necessary if permittivity combination of laser
structures is properly designed. Here, we experimentally demonstrate
a SPP nanolaser with a ZnO nanowire on the as-grown single-crystalline
aluminum. The average lasing threshold of this simple structure is
20 MW/cm<sup>2</sup>, which is four-times lower than that of structures
with additional insulator layers. Furthermore, single-mode laser operation
can be sustained at temperatures up to 353 K. Our study represents
a major step toward the practical realization of SPP nanolasers