How photodiode detect light?

A photodiode detects light by utilizing the photovoltaic or photoconductive effect. When light photons hit the semiconductor material of the photodiode, they generate electron-hole pairs, which create a current proportional to the intensity of the light. In photovoltaic mode, this creates a voltage across the diode, while in photoconductive mode, the resistance of the diode decreases, allowing more current to flow. This change in current or voltage can then be measured to quantify the light intensity.