Aluminium nanoparticle-based ultra-wideband high-performance polarizer

Area of Science:

• Nanophotonics
• Plasmonics
• Optical Engineering

Background:

• The growing polarizer device industry demands high-performance nanoscale wideband polarizers.
• Metals are attractive for reflection-based polarizers due to their high extinction ratios.
• Existing wideband polarizers often face limitations in performance and scalability.

Purpose of the Study:

• To investigate the potential of aluminum (Al) dimer nanostructures for creating novel broadband polarizers.
• To design and simulate a nanoparticle polarizer using semi-immersed Al nano-dimers.
• To evaluate the performance of the proposed Al nano-dimer polarizer in the near-infrared (NIR) and Terahertz (THz) ranges.

Main Methods:

• Utilized finite-difference time-domain (FDTD) simulations for rigorous analysis.
• Designed a novel polarizer comprising semi-immersed Al nano-dimers (200 nm radius) on a CaF2 substrate.
• Calculated key performance parameters: extinction ratio (ER), insertion loss, Mueller matrix values, and polarization ellipse.

Main Results:

• The proposed Al nano-dimer polarizer demonstrated significant polarization anisotropy in NIR and THz frequencies.
• Achieved an extinction ratio exceeding 55 dB over the 0.2 to 9 THz range.
• In the THz range, extinction ratios reached up to 60 dB, outperforming conventional wire-grid polarizers.
• Average ER of 29.01 dB and insertion loss of ~1 dB were observed from 1 to 1665 μm.

Conclusions:

• Al dimer nanostructures present a promising avenue for developing advanced micro-scale metallic wideband polarizers.
• The proposed design offers superior performance, particularly in the THz spectrum, compared to existing technologies.
• This research provides valuable insights for future wideband polarizer development.