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 nanoparticle polarizer comprised of semi-immersed Al nanodimers with a 200 nm radius on a CaF_2 substrate. Our proposed polarizer has effective polarization anisotropy in the near-infrared (NIR) and THz range. 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. The average extinction ratio and insertion loss over the 1-1665 micrometer wavelength were 29.01 dB and ~1 dB, respectively. We have reviewed recent reports of similar nanoparticle and wire grid-based polarizers to evaluate our Al nanodimer-based polarizer and performed a comparative analysis. 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.