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I Why do Lasers need to be cooled?

  1. Apr 9, 2016 #1
    Why do Lasers need to be cooled?

    I understand say, optical pumping with a flashlamp will cause a lot of waste in the form of heat. Is this heat in the lasing medium or in the flashlamp itself?

    I'm trying to understand where the waste heat actually goes, and why the laser needs to be cooled after use?
  2. jcsd
  3. Apr 9, 2016 #2


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    Overheat in a laser medium can lead to thermo-optical effect such as thermal-induced stress. This effect further causes birefringence in the gain medium, which is an generally adverse effect as it can modify the polarization profile of the laser beam.
  4. Apr 10, 2016 #3


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    Offhand, I would think that it goes in both the lamp and the medium. I confess I don't know what percentage of heat goes where or anything.
  5. Apr 11, 2016 #4
    An optically pumped laser, generally gets pumped with a broad spectrum of light, of which only
    a small amount is the right wavelength to be absorbed by the lasing medium.
    All the rest of the wavelength are unused and will eventually turn to heat which must be removed.
    Of the wavelengths that are absorbed, only some of the quantum decay states are useful
    for producing the selected laser wavelength, the rest still represent energy that must be removed
    from the system.
    In the diagram below what they describe as broad optical absorption, is not as broad as the light source.
    Also the state change from 3 to 2 still represents an energy release, which must be dealt with.
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