How Is Laser Power Output Measured?

One specification that is always in the description of lasers is its power level, but have you ever wondered how these laser manufacturers measure laser power?

There are a lot of different ways to measure this parameter. Three technologies are often found in industrial power detectors: photodetectors, thermopiles and water calorimeters.

Let me present how each technology works as well as their advantages and disadvantages.

Laser Power Measurement With Photodetectors

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.