Photosensors or photodetectors are sensors of light or other electromagnetic energy. A photo detector converts light signals that hit the junction into voltage or current. The connection uses an illumination window with an anti-reflect coating to absorb the light photons. This results in creation of electron-hole pairs in the depletion region. Photodiodes and photo transistors are few examples of photo detectors. Solar cells are also similar to photo detectors as they absorb light and turn it into energy.
There are a range of different types of light sensors, including 'Photoresistors', 'Photodiodes', and 'Phototransistors'.