Ultrathin reflecting wideband terahertz cross polarization converter as a biosensor

Abstract

This work presents an ultrathin terahertz linear cross polarization converter (LCPC) with a unit cell volume of 0.125λ_L × 0.125λ_L × 0.67λ_L (λ_L= wavelength at 3.1285 THz). The unit cell consists of a metallic resonator composed of two l-shaped structures, a center cross-shaped structure, a dielectric material, and a metallic ground plane. The suggested LCPC has a Polarization Converter Ratio (PCR)≥80 % from 3.1285 THz to 9.6 THz with an FWHM of 6.776 THz. This polarization converter transforms x-polarized to y-polarized waves and vice versa. The PCR≥80 % bandwidth and PCR≥90 % peaks are almost unaffected for incident angle(θ)≤20° and θ≤45°, respectively, at 3.34, 5.15, 7.92, and 9.42 THz. The LCPC's equivalent circuit model (ECM) results agree with the simulated results. This LCPC-based biosensor detects blood cancer, basal skin cell cancer, and TB with a maximum sensitivity of ∼0.9302 THz/RIU, ∼0.9441 THz/RIU, and ∼0.9554 THz/RIU respectively.