Double-Layer Sandwich Metasurface for Mid-Infrared Multi-Channel Polarization Detection

Conventional snapshot-type polarization devices often suffer from inherent ohmic losses caused by the metal structure, resulting in low utilization of system light energy. This research proposes a dual-layer sandwich architecture metasurface that integrates polarization control and high light transmittance for the mid-wave infrared 3~5 μm band. The top metal polarization-selective structures and the bottom dielectric hemispherical anti-reflection (AR) array are integrated monolithically on the same substrate. Specifically, the numerical simulations predict a peak transmittance of 95% at 4.4 and 4.8 μm, while maintaining extinction ratios ranging from 81.8 dB to 84.3 dB. This enables high extinction ratio polarization splitting while significantly broadening the transmittance flux of the device. It breaks the inherent trade-off between “high extinction ratio” and “high transmittance” in polarization devices, providing a high signal-to-noise ratio hardware foundation for high temporal resolution detection.