Second and third generation thermal imagers based on type-II superlattice photodiodes

We report on the development of InAs/GaSb type-II superlattice focal plane arrays (FPAs) for missile warning systems in airborne platforms. The FPA fabrication technology was developed on the basis of monospectral superlattices for the MWIR (3-5 μm) spectral range. A monospectral 288×384 MWIR camera with 24 μm pixel pitch, a noise equivalent temperature difference (NETD) better than 14 mK and a background-limited performance (BLIP) up to 92 K is demonstrated. Based on the monospectral technology, the first bispectral superlattice camera was realized. The dual color 288×384 superlattice camera features simultaneous, pixel-registered detection of both spectral channels between 3-4 μm and 4-5 μm with a NETD better than 30 mK and 17 mK, respectively. Hence, spatial or temporal registration problems, which are common to most dual color and dual band infrared imagers are solved with the new bispectral MWIR missile alerting sensor.