Responsivity

Responsivity: In a photodetector, the ratio of the electrical output to the optical input.

Note 1: Responsivity is usually expressed in amperes per watt, or volts per watt, of incident radiant power.

Note 2: Responsivity is a function of the wavelength of the incident radiation and the bandgap of the material of which the photodetector is made. Deprecated synonym sensitivity.

Source: from Federal Standard 1037C and from MIL-STD-188