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About laser physics

  1. May 15, 2009 #1


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    What does saturation mean in laser physics? I am reading some material on two-level system, in which it mentions something call "saturating pump field", what does this field mean?
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  3. May 15, 2009 #2

    Andy Resnick

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    In the two-state approximation (ground state and excited state), a pump field can move atoms from the ground state to excited state. When the efficiency of pumping goes to zero (which is reached at a 50-50 population distribution, IIRC), the laser medium is said to be 'saturated'- no additional atoms can be moved into the excited state without some returning to the ground state.

    Population inversion (lasing with gain) requires at least three states.
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