Highly Sensitive and Cost-Effective Polymeric-Sulfur-Based Mid-Wavelength Infrared Linear Polarizers with Tailored...

Inverse-vulcanized polymeric sulfur has received considerable attention for application in waste-based infrared (IR) polarizers with high polarization sensitivities, owing to its high transmittance in the IR region and thermal processability. However, there have been few reports on highly sensitive polymeric sulfur-based polarizers by replication of pre-simulated dimensions to achieve a high transmission of the transverse magnetic field (T_TM ) and extinction ratio (ER). Herein, a 400-nanometer-pitch mid-wavelength infrared bilayer linear polarizer with self-aligned metal gratings is introduced on polymeric sulfur gratings integrated with a spacer layer (SM-polarizer). The dimensions of the SM-polarizer can be closely replicated using pre-simulated dimensions via a systematic investigation of thermal nanoimprinting conditions. Spacer thickness is tailored from 40 to 5100 nm by adjusting the concentration of polymeric sulfur solution during spin-coating. A tailored spacer thickness can maximize T_TM in the broadband MWIR region by satisfying Fabry-Pérot resonance. The SM-polarizer yields T_TM of 0.65, 0.59, and 0.43 and ER of 3.12 × 10³ , 5.19 × 10³ , and 5.81 × 10³ at 4 µm for spacer thicknesses of 90, 338, and 572 nm, respectively. This demonstration of a highly sensitive and cost-effective SM-polarizer opens up exciting avenues for infrared polarimetric imaging and for applications in polarization manipulation.