A compact polarization-integrated long wavelength infrared focal plane array based on InAs/GaSb superlattice

Real-time polarization imaging plays a vital role in target detection, recognition, and tracking in complex scenes. However, large optical crosstalk and the integration technology are difficult problems in the development of polarization-integrated infrared detectors. We demonstrate a monolithic long wavelength infrared (LWIR) InAs/GaSb superlattice focal plane array (FPA) integrated with the polarizer. To obtain high performance and real-time polarization imaging device, the parameters of the grating were optimized and the optical crosstalk between adjacent polarization bands was studied. We analysis the light diffraction depending on the distance between the polarizer and photosensitive elements, and the coupling between oblique incident light and device. The fabrication process of the antireflective polarizer, the integration technology of polarizer and the FPA composed of 512×4×3 pixels were explored. Finally, a polarization integrated focal plane array (PI-FPA) was fabricated to detect polarized light with different oscillating directions. The large response extinction ratio of corresponding polarization bands was measured as 50:1, 49:1, and 44:1 of 0°, 60°, and 120°, respectively.