Sub-diffractional waveguiding by mid-infrared plasmonic resonators in semiconductor nanowires

Area of Science:

• Nanophotonics
• Plasmonics
• Materials Science

Background:

• Chains of nanoscale plasmonic resonators enable sub-diffractional waveguiding.
• Practical applications are hindered by high optical losses and low group velocities.

Purpose of the Study:

• To predict the waveguide performance of plasmonic resonators embedded in high-dielectric nanowires.
• To identify strategies for overcoming limitations in plasmonic waveguiding.

Main Methods:

• Numerical simulations of doped silicon (Si) plasmonic resonators in intrinsic Si nanowires.
• Investigation of resonator aspect ratio, doping, and spacing effects.
• Development of an analytical "absorption spectra" method for analyzing coupled resonators.

Main Results:

• Group velocities and propagation lengths increased by up to an order of magnitude compared to vacuum.
• Maximized propagation lengths observed for large aspect ratios, high dopant concentrations, and small spacings.
• The "absorption spectra" method effectively extracts waveguide information from far-field absorption data.

Conclusions:

• Plasmonic resonators in high-dielectric nanowires offer a promising route to improved waveguiding performance.
• Optimized resonator design and material parameters can significantly enhance group velocities and propagation lengths.
• The "absorption spectra" method provides a novel and efficient tool for characterizing plasmonic waveguides.