A photodiode is an electronic component that can detect light by converting light into either current or voltage depending on the application, and is a type of photodetector. The two terminals are called the anode (the arrow side) and the cathode (the bar side) and the normal mode of operation is in the reverse biased direction when the anode is negative and the cathode is positive.
Photodiodes is used as photodetectors in varies applications:
- Receivers for infrared remote controls.
- Smoke Detectors
- Digital isolation circuits where inputs are isolated from the main circuit.
- Various sensors to measure speed and obstructions.