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

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Inverse-vulcanized polymeric sulfur is promising for infrared (IR) polarizers due to high IR transmittance and thermal processability.
• Previous polymeric sulfur polarizers lacked high sensitivity, transmission of transverse magnetic field (T_TM), and extinction ratio (ER) due to challenges in replicating precise dimensions.

Purpose of the Study:

• To develop a highly sensitive mid-wavelength infrared (MWIR) bilayer linear polarizer using polymeric sulfur and self-aligned metal gratings.
• To optimize the polarizer's dimensions via thermal nanoimprinting and tailor spacer thickness for enhanced performance.

Main Methods:

• Fabrication of a 400-nanometer-pitch MWIR bilayer linear polarizer on polymeric sulfur gratings with a spacer layer (SM-polarizer).
• Systematic investigation of thermal nanoimprinting conditions to replicate pre-simulated dimensions.
• Tailoring spacer thickness (40–5100 nm) by adjusting polymeric sulfur solution concentration during spin-coating.

Main Results:

• The SM-polarizer dimensions were closely replicated using pre-simulated designs.
• Tailored spacer thickness maximized T_TM in the broadband MWIR region by achieving Fabry-Pérot resonance.
• At 4 µm, T_TM of 0.65 and ER of 3.12 × 10³ were achieved with 90 nm spacer thickness; T_TM of 0.59 and ER of 5.19 × 10³ with 338 nm; T_TM of 0.43 and ER of 5.81 × 10³ with 572 nm.

Conclusions:

• A highly sensitive and cost-effective SM-polarizer was demonstrated.
• The developed polarizer shows significant potential for infrared polarimetric imaging.
• This work opens new avenues for polarization manipulation applications in the infrared spectrum.