Photodiode

Photodiode

A P-N junction designed to be responsive to optical input. Photodiodes are provided with either a window or optical fibre connection, in order to let in the light to the sensitive part of the device.

Normally operated in reverse bias, when in darkness, the photodiode will conduct little or no electric current. As the intensity of the light increases, the current through the diode will increase in preportion. Thus a photodiode provided a means for an electrical system to detect an optical input.

Uses. Any situation where an electrical system is required to respond to light. Eg. (there are a lot of uses, this is a tiny sample)

Turning street lights on when it gets dark.

Automatic control of a camera according to how light or dark the scene being photographed is.

As a detector in an optical transmission system.

See also silicon photodiode, light-dependent resistor