https://cs.nyu.edu/~jhan/ledtouch/index.html
A few days ago, a user here also commented on how LEDs work both ways and how he used this effect to automatically adjust the brightness of an LED to ambient light. You can find that comment here:
“…and in my next video I’ll show you how to bake a pizza in your freezer.”
With reverse-biased diodes, you are operating in photoconduction mode. If tightly-coupled to a fiber optic, and with a quantum efficiency of say, 10%, that would mean for every 10 photons which come in, you get 1 electron charge of current flow.
IIRC there are people who paint e.g. 1N4444 diodes with black paint to minimize opto-induced leakage.
