Photodetector Responsivity: Definition and Parameters

This page covers the definition of responsivity of a photodetector. Responsivity is used to measure the input-output gain of the detector in a fiber optic system. In the case of a photodetector, it’s the measure of electrical output per optical input.

Most photodetectors exhibit a linear relationship with the input incident power. The responsivity of a photodetector is typically expressed in units of amperes per watt (A/W) or volts per watt (V/W) of radiant power.

The responsivity of a photodetector depends on the following parameters:

• Wavelength of incident radiation
• Sensor properties, e.g., bandgap of the material