Aluminium nanoparticle-based ultra-wideband high-performance polarizer.

The polarizer-based device industry is expanding quickly, requiring high-quality research on nanoscale wideband polarizers. Here, we investigated the possibility of utilizing Al dimer nanostructures on broad-band polarizers. Metals are always considered promising candidates for reflection-based polarizer development because of their high extinction ratio. This study proposes a novel nanoparticle polarizer comprised of semi-immersed Al nano-dimers with a 200 nm radius on a CaF substrate. Our proposed nano-dimer-based design demonstrated impressive polarization anisotropy in the near-infrared (NIR) and THz ranges than conventional wire-grid-based ones. This study includes calculating performance parameters for the extraction of the proposed polarizer, including insertion loss, extinction ratio (ER), Mueller matrix values, and polarization ellipse diagram. The finite-difference time-domain (FDTD) simulation-based results suggested obtaining more than 55 dB extinction ratio for the 0.2 to 9 THz range. In the THz region, simulation results suggest impressively better performance than conventional wire-grid polarizers. In THz frequency range, our proposed polarizer demonstrated its extinction ratio of up to 60 dB. The average extinction ratio and insertion loss over the 1-1665 μm wavelength were 29.01 dB and ∼1 dB, respectively. The idea of Al dimer and the insight gained from the results extracted from the rigorous simulation report suggested a great opportunity for developing micro-scale metallic wideband polarizers.