Eindhoven University of Technology has made a photodiode with such low noise (<10-6mA/cm2 dark current) and wide dynamic range (<150dB), that it can optically detect a heartbeat at a distance of 1.3m.
Through an unexpected photo-multiplier effect, it can achieve a photo-electron yield above 200% at 850nm.
“I know, this sound incredible,” said project researcher Professor René Janssen, “but, we’re not talking about normal energy efficiency here. What counts in the world of photodiodes is quantum efficiency, the number of photons that the diode converts into electrons.”