High SNR eSWIR Image Sensor Applied in Advanced Hyperspectral Imager Aboard China’s GaoFen-5 Satellite and ZY-1 Satellite

This article presents an extended short-wave infrared (eSWIR) image sensor, a large-format infrared focal plane array (IRFPA), applied in Advanced Hyperspectral Imager (AHSI) aboard China’s three GaoFen-5 satellites and two more followed ZY-1 satellites. Hyperspectral imaging has been emerged as a very important application in Earth observation instruments, for the spectral detection provides the spectrum information of ground objects except for the spatial imaging of the objects. AHSI has a 60-km swath width and a 30-m spatial resolution, and has high signal-to-noise ratio (SNR) in spectrum of interest. Large-format IRFPAs which are ordinarily used in staring IR imaging have some special performance requirements when applied in hyperspectral imaging, such as higher quantum efficiency (QE), lower dark current, lower noise, and selectable current conversion gain to match the different radiation flux of different subdivided spectral bands. We developed a format of $2048\times 512$ HgCdTe/Si IRFPA sensor (equivalent $2012\times 256$ after pixel overlapping and binning) in which 2012 pixels meet the demands of 60-km swath width and 256-pixel lines meet the 200 spectral bands. The sensor has eight-level gains selectable by spectral bands, array dark current densities on the order of $10^{-10}$ A/cm2, QE exceeding 80%, and the operability of 99.5% at the operating temperature of around 110 K. The SNR of this FPA achieved 150 when illuminated under $5\times 10^{4}$ photons/pixel.