In this presentation, we will report our recent efforts in achieving high performance in Antimonides type-II superlattice (T2SL) based infrared photodetectors using the barrier infrared detector (BIRD) architecture. The high operating temperature (HOT) BIRD focal plane arrays (FPAs) offer the same high performance, uniformity, operability, manufacturability, and affordability advantages as InSb. However, mid-wavelength infrared (MWIR) HOT-BIRD FPAs can operate at significantly higher temperatures (<150K) than InSb FPAs (typically 80K). Moreover, while InSb has a fixed cutoff wavelength (~5.4 μm), the HOT-BIRD offers a continuous adjustable cutoff wavelength, ranging from ~4 μm to <15 μm, and is therefore also suitable for long wavelength infrared (LWIR) as well. The LWIR detectors based on the BIRD architecture has also demonstrated significant operating temperature advantages over those based on traditional p-n junction designs. Two 6U SmalSat missions CIRAS (Cubesat Infrared Atmospheric Sounder) and HyTI (Hyperspectral Thermal Imager) are based on JPL’s T2SL BIRD focal plane arrays (FPAs). Based on III-V compound semiconductors, the BIRD FPAs offer a breakthrough solution for the realization of low cost (high yield), high-performance FPAs with excellent uniformity and pixel-to-pixel operability. We have also exploring the possibilities of integrating either metasurface resonator cavity or metasurface based flatlens with individual pixels to improve the signal-to-noise ratio of the detectors. Furthermore, we will discuss the advantages of the utilization of all digital read out integrated circuits with HOT-BIRDs.
Copious Imaging is commercializing a digital-readout integrated circuit (DROIC) technology that not only digitizes, but also performs computations on the signal at each pixel. When the DROIC is mated to a photodiode detector array, the device forms a Computational Pixel Imager (CPI). The technology was in development for many years at MIT Lincoln Laboratory, and now also at Copious Imaging for new application areas. CPI technology is fundamental to the operation of WISP – the Wide-Area Infrared System with Persistence. WISP is a 500-Mpix longwave infrared (LWIR) motion imaging sensor that produces imagery covering the complete surroundings, more than 2π steradians, every 2 seconds. WISP utilizes a fast scanner to cover the scene quickly. The WISP sensor is coupled with a real-time processing system that stiches the scene together from scanned swaths, performs a non-uniformity compensation, stabilizes the imagery to sub-pixel accuracy, detects motion, and tracks all moving objects of interest. The system has machine learning built-in to aid in identifying objects of interest while ignoring clutter. WISP is in use for many applications and in development for several more. We are currently evaluating WISP for use in screening for fevers.