Question

Short note on photo detector(Definition, classification,detailed explanation of any photo detector)

Answer 1

Answer:

Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. A photo detector has a p–n junction that converts light photons into current. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors.

Explanation:

Answer 2

Answer:

here it is mate

Explanation:

Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation.[1] A photo detector has a p–n junction that converts light photons into current. The absorbed photons make electron–hole pairs in the depletion region. Photodiodes and photo transistors are a few examples of photo detectors. Solar cells convert some of the light energy absorbed into electrical energy.Photodetectors may be classified by their mechanism for detection:[2][unreliable source?][3][4]

Photoemission or photoelectric effect: Photons cause electrons to transition from the conduction band of a material to free electrons in a vacuum or gas.

Thermal: Photons cause electrons to transition to mid-gap states then decay back to lower bands, inducing phonon generation and thus heat.

Polarization: Photons induce changes in polarization states of suitable materials, which may lead to change in index of refraction or other polarization effects.

Photochemical: Photons induce a chemical change in a material.

Weak interaction effects: photons induce secondary effects such as in photon drag[5][6] detectors or gas pressure changes in Golay cells.

Photodetectors may be used in different configurations. Single sensors may detect overall light levels. A 1-D array of photodetectors, as in a spectrophotometer or a Line scanner, may be used to measure the distribution of light along a line. A 2-D array of photodetectors may be used as an image sensor to form images from the pattern of light before it.

A photodetector or array is typically covered by an illumination window, sometimes having an anti-reflective coating.