Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications

Polyethylene is a promising polymer for mid-infrared integrated optics due to its broad transparency and optimal refractive index. However, simple fabrication protocols that preserve optical characteristics are needed foster wide range of applications unlock full potential. This work presents investigations the structural properties spin-coated linear low-density polyethylene films fabricated under humidity-controlled conditions. The film thickness on concentration dependence shows non-linear behavior, in agreement with previously reported theoretical models allowing predictive concentration-dependent deposition high repeatability. surface roughness nanometer-scale all investigated concentrations between 1% 10%. crystallinity was studied Raman spectroscopy technique. Mid-infrared ellipsometry measurements show as expected bulk material. Layer exposure solvents revealed good stability films, indicating layers can outlast further steps. These confirm excellent thin our novel method, creating new opportunities use photonic circuits