Temperature-resilient anapole modes associated with TE polarization in semiconductor nanowire

Abstract

Polarization-dependent scattering anisotropy of cylindrical nanowires has numerous potential applications in, for example, nanoantennas, photothermal therapy, thermophotovoltaics, catalysis, sensing, optical filters and switches. In all these applications, temperature-dependent material properties play an important role and often adversely impact performance depending on the dominance of either radiative or dissipative damping. Here, we employ numerical modeling based on Mie scattering theory to investigate and compare the temperature and polarization-dependent optical anisotropy of metallic (gold, Au) nanowires with indirect (silicon, Si) and direct (gallium arsenide, GaAs) bandgap semiconducting nanowires. Results indicate that plasmonic scattering resonances in semiconductors, within the absorption band, deteriorate with an increase in temperature whereas those occurring away from the absorption band strengthen as a result of the increase in phononic contribution. Indirect-bandgap thin (20 nm) Si nanowires present low absorption efficiencies for both the transverse electric (TE, E ⊥ ) and magnetic (TM, E ) modes, and high scattering efficiencies for the TM mode at shorter wavelengths making them suitable as highly efficient scatterers. Temperatureresilient higher-order anapole modes with their characteristic high absorption and low scattering efficiencies are also observed in the semiconductor nanowires (r = 125−130 nm) for the TE polarization. Herein, the GaAs nanowires present 3−7 times greater absorption efficiencies compared to the Si nanowires making them especially suitable for temperature-resilient applications such as scanning near-field optical microscopy (SNOM), localized heating, non-invasive sensing or detection that require strong localization of energy in the near field.

Design and construct full invisible band metamaterial-based coating with layer-by-layer structure in the microwave range from 8 to 10 GHz

“…A current project in collaboration with the University of Pennsylvania and Stanford University aims to build a detector in the visible light frequency range. The basis of this structure is that they coat the silicon nanowires with a gold layer [17,18]. By adjusting the amount of gold and dimensions in this structure, light reflected from metal and semiconductor are neutralized.…”

“…Now, by using constitutive relations in vacuum space (equation ( 16)) and the rules of index displacement (equation ( 17)) [34,37] and equations (10), ( 15) is rewritten as equation (18) for right-handed coordinates systems…”