LWIR QWIPs at IRnova for next generation polarimetric imaging

Abstract

Polarization sensitive quantum well infrared photodetector (QWIP) focal plane arrays (FPAs) with 30 and 15 µm pitch sizes are fabricated with wire grid polarizers monolithically integrated on the pixels. High polarization contrast is achieved for pixels with 30 µm pitch size, 0.58 ± 0.05 depending on the grating orientation, with good spatial homogeneity (standard deviation below 0.01). The polarization contrast drops to 0.30 ± 0.05 for 15 µm pixel pitch. Influence of the grating orientation on the optical responsivity and the polarization contrast has been evaluated showing the strongest impact for +45° orientations. The fabricated FPAs exhibit temporal and spatial Noise Equivalent (NE) Degree of Linear Polarization (DoLP) of 0.03% and 0.23%, respectively, setting the resolution limit of DoLP to 0.4%. Capability of the fabricated FPAs to image polarimetric signatures in the dynamic scenes with high frame rate has been demonstrated.