A Thermally Stable, Infrared-Transparent High-Sulfur-Containing Polymer for High Aspect-Ratio Nanostructured MWIR...

Area of Science:

• Materials Science
• Optics
• Polymer Chemistry

Background:

• Infrared (IR) polarizers are crucial for thermal imaging in defense and mobility.
• Existing inorganic IR polarizers are brittle and costly.
• High-sulfur polymers offer mid-wave IR (MWIR) transparency but suffer from poor thermal stability.

Purpose of the Study:

• To develop a thermally stable and high-performance glassy IR polarizer.
• To explore the potential of poly(sulfur-co-hexavinyl disiloxane) (pSHVDS) for IR applications.
• To demonstrate fabrication of nano-grating patterns for enhanced polarization.

Main Methods:

• Synthesized a highly crosslinked sulfur-rich polymer, pSHVDS, using sulfur chemical vapor deposition (sCVD).
• Utilized self-crosslinking of pSHVDS for thermal stability during nanoimprint lithography.
• Fabricated high-fidelity nano-grating patterns with specific dimensions (400 nm pitch, 150 nm width, 300 nm height).

Main Results:

• Achieved over 50% transmittance (T_TM) and an extinction ratio (ER) exceeding 6000 across a broad IR range (3-8 µm).
• Enhanced T_TM to 84% and ER to 7200 at 4 µm with an anti-reflection coating.
• Demonstrated exceptional thermal stability, maintaining performance after 24 hours at 100°C.

Conclusions:

• Glassy pSHVDS-based polarizers show significant potential for advanced IR applications.
• The developed material offers the highest ER reported for organic MWIR polarizers.
• The fabrication method enables high-performance, thermally stable IR polarizers.