Satellites and high-altitude balloons could soon communicate using avalanche photodiodes (APD) developed by Leti, a CEA Tech institute. Mynaric Lasercom, which specializes in optical space and airborne communication networks, recently signed an exclusive R&D contract with Leti to develop and scale up high-sensitivity, ultra-fast sensors to enable optical communications over very long distances at the lowest possible cost.

Optical space and airborne communication uses the propagation of light (either visible or infrared) to transmit data between two points. The data are coded and sent by a laser; the light is then received by a photodetector, which converts it into an electrical signal. In the best cases, conventional photodiodes produce one electron for each photon received. Avalanche photodiodes produce several electrons, intensifying the perceived signal.

Leti drew on four decades of experience in high-sensitivity IR detectors to develop HgCdTe-based APDs, which can currently amplify the intensity of a signal 100- to 200-fold without generating parasite noise—unlike some competing APD technologies. The detector structure and electronic signal processing must now be improved for very-high-speed operation at temperatures compatible with the target applications.