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Pump Parameter

Definition: the ratio of pump power and threshold pump power of a laser

German: Pumpparameter

Category: lasers

Units: (dimensionless number)

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The pump parameter r of a laser is the ratio of pump power and threshold pump power. Usually, this quantity is used for optically pumped lasers.

Most lasers are operated with a pump parameter between 3 and 10, i.e. significantly but not very far above threshold. This is because extreme values often have some disadvantages:

Extreme values of pump parameters are nevertheless required in some cases:

Particularly in the context of four-level lasers, it can be convenient to use the pump parameter r in equations, as it is most easy to evaluate in an experiment, and thus often well known. In four-level lasers, the intracavity optical intensity in the gain medium (in the steady state, assuming a flat-top mode profile) is (r − 1) times the saturation intensity. Also, there is a simple equation for the frequency of relaxation oscillations, containing the parameter r. However, such equations then often do not hold for (quasi-)three-level gain media.

See also: threshold pump power, lasers, relaxation oscillations, four-level and three-level gain media, The Photonics Spotlight 2007-01-21
and other articles in the category lasers


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