March, 2023: Photodetectors are mainly used for power in the picowatt to milliwatt range. They are made from semiconductors with a p-n junction that converts photons coming from a light source into an electric current. The more photons available, higher is the current.
The wavelength range of a photodetector depends on the semiconductor used. For example, Germanium photodetectors are often used with the 1550 nm wavelength that is used in telecommunication since it is compatible with this wavelength.
Photodetectors have a short response time which makes them the preferred choice in applications where power variations need to be quickly monitored. Even if photodetectors are made for lower powers, it is possible to add attenuation, a pick-off or an integrating sphere in order to use photodetectors at higher power.
One of the downsides of these detectors is their absorption that depends on the wavelength. It is important to select the correct wavelength; otherwise, the measurement will be way off. A good example of photodetectors is our PH series.