Tunable High Refractive Index Polymer Hybrids for IR Optical Components

ABSTRACT:Physical Sciences Inc. will design and produce a tunable high refractive index polymer composite by dispersing precise amounts of high refractive index nanocrystals into a novel sulfur-rich polymer. This proposed technology will yield a base polymer with a refractive index eta > or = 1.8 and IR transparency (alpha <0.25 cm-1) from 3 - 5 um by utilizing non-hydrocarbon chemistries during polymer synthesis and optics fabrication. Further doping with high refractive index (eta = 5.0) nanoparticles will boost the refractive index above eta = 2.0 at loadings of 10 vol%, and provides a straightforward route to tunable refractive index infrared optics. This approach will deliver a robust polymeric material with optical properties comparable to state-of-the-art semiconductor and chalcogenide glasses, but at a fraction of the cost, and with the scalability of polymer processing. In Phase I the approach will be validated by fabricating a proof-of-concept optical window by melt processing to meet Air Force specifications.In Phase II we will pursue (1) polymer composite scale up, (2) application of antireflection coatings (R<1%) to the composite surface, and (3) development of low-cost plastics manufacturing techniques such as block casting and polishing, injection molding, and 3D printing for the production of IR optics.BENEFIT:This technology will advance IR imaging science and offer a low cost, light weight, and robust IR transparent alternatives to heavy, expensive, and fragile semiconductor and chalcogenide glass optical components. The market for a successful high refractive index IR transparent polymer is currently expansive in civil, military, and medical areas. Applications that would utilize this technology include thermal imaging and missile systems, FLIR, hyperspectral imaging, spectroscopy, and QCL lasers. The ability to precisely tune the shape and refractive index would also prove useful for photonic applications that require components with specific size, shape, and refractive index.