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He-Ne LASER Action Clarifications

  1. Apr 12, 2014 #1
    1. Won't the electrons get knocked out of the atom during the pumping action instead of just getting excited to higher energy level in LASERS?

    2. why doesn't the electron in meta stable state(higher energy state) go to much higher energy level during STIMULATED emission instead of losing energy and emitting a photon? This is the opposite of ionization of the atom, if I'm not wrong.

    3.Finally, what happens to the light emitted by spontaneous emission in HE-Ne laser? Won't it mix with the LASER light?
    Last edited: Apr 12, 2014
  2. jcsd
  3. Apr 12, 2014 #2


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    I guess that can happen, but it does not contribute to the laser action.
    Stimulated emission means it emits an additional photon, so it has to lose energy.
    There is no higher energy level with the right energy difference to reach with those photons.
    No, as there are no free electrons involved.
    It is part of the emitted light, yes.
  4. Apr 12, 2014 #3
    Thanks mfb for the response. I have got one more question.

    When we say the LASER is coherent, what does it mean? What does it mean to be non-coherent? What does a monochromatic, non-divergent and COHERENT light has that a monochromatic, non-divergent and NON-COHERENT lacks? Does it have less number of photons per unit area per unit time or is it energy of each photon is it something else?
  5. Apr 12, 2014 #4


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