The detector sensitivity of a photodiode refers to its ability to convert incident light or photons into an electrical current or voltage. It quantifies how effectively the photodiode responds to incoming photons and generates a measurable electrical signal in response to light. Detector sensitivity is an important parameter in photodiode specifications because it determines the ability of a photodiode to detect and measure light intensity.

Detector sensitivity is typically expressed in terms of the responsivity of the photodiode, which is a measure of the photocurrent or voltage generated per unit of incident optical power. Responsivity is often denoted by the symbol R and is usually expressed in units of ampere per watt (A/W). It is calculated as,

The responsivity (detector sensitivity) of a photodiode can vary depending on factors such as the wavelength of light, the material from which the photodiode is made, and the design of the photodiode. Photodiodes are typically characterized across a specific wavelength range, and their responsivity can be plotted as a function of wavelength in a responsivity spectrum.