Understanding all-dielectric periodically modulated coatings for normal-incidence polarization control

An ultracompact thin-film polarizer for normal-incidence (0° angle of incidence, AOI) applications is analytically and experimentally investigated. The device is based on Fano resonances in periodically nanostructured dielectric thin films, enabling polarization selective reflection and transmission due to polarization dependent resonance frequencies. The operating principle is analyzed both analytically and numerically, and the optimized structure is fabricated and experimentally characterized. Measurements demonstrate polarization contrast ratios of up to approximately 1:1000 at normal incidence. Laser-induced damage threshold measurements using nanosecond laser pulses further confirm the high damage resistance of the all-dielectric polarizer.