There have been no significant breakthroughs in infrared imagery since the hybridization of III-V or II-VI narrow-bandgap semiconductors on complementary metal-oxide semiconductor (CMOS) read-out integrated circuits (ROICs). The development of third-generation, linear-mode avalanche photodiode arrays (LmAPDs) using mercury cadmium telluride (MCT) has resulted in a significant sensitivity improvement for short-wave infrared (SWIR) imaging. The first dedicated LmAPD device, called SAPHIRA (320x256/24μm), was designed by Leonardo UK Ltd specifically for SWIR astronomical applications requiring speed and sensitivity. In the past decade there has been a significant development effort to make larger LmAPD arrays for low-background astronomy and advance adaptive optics.

Larger LmAPD formats for ultra-low noise/flux SWIR imaging, currently under development at Leonardo include a 512 x 512 LmAPD array funded by ESO, MPE and NRC Herzberg, a 1k x 1k array funded by NASA and a 2K x 2K device funded by ESA for general scientific imaging applications. The 2048x2048 pixel ROIC has a pitch of 15 microns, 4/8/16 outputs and a maximum frame rate of 10 Hz.

The ROIC characterization is scheduled in the third quarter of 2022, while the first arrays will be fabricated by end-2022. The hybridized arrays will be characterized during end-2022. At this time, First Light Imaging will start the development of an autonomous camera integrating this 2Kx2K LmAPD array, based on the unique experience from the C-RED One camera, the only commercial camera integrating the SAPHIRA SWIR LmAPD array. The main features of this camera is presented. The detector will be embedded in a compact high vacuum cryostat cooled with low vibration pulse at 50-80K which does not require external pumping. If necessary, an active vibration damping system can be added for reducing the array vibrations down to 0.01 micron. Sub-electron readout noise is expected to be achieved with high multiplication gain. Custom cold filters and beam aperture cold baffling will be integrated in the camera.