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Stimulated Emission by Laser discussion

  1. Nov 28, 2011 #1
    I'm doing a very short presentation on a laser. I want to discuss the most important concepts of a laser (in less than ten minutes). What should I include?

    I was thinking about stimulated emission and amplification. (But I'm not sure I really grasp these concepts)

    For instance, does stimulated emission occur only in a laser? Is it a rare thing? Is stimulated emission the reason why the photons experience amplification?

    Also, what role do the mirrors play? Are the mirrors the reason the beam is collimated? Or do the mirrors act to induce the semi-isolated system of the laser that allows for stimulated emission?

    Any helpful information would be great!!!
  2. jcsd
  3. Nov 28, 2011 #2


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    Stimulated emission only occurs in lasers, as it takes very specific circumstances to occur. (Or rather it only occurs in large quantities in a laser. It has a small chance of happening in nature)

    The amplification by stimulated emission in a laser refers to light of a certain frequency causing excited electrons to fall to a lower energy state and emit another photon of the same frequency as the first. So the original beam of photons is quickly reinforced and amplified by additional photons.

    I believe the mirrors bounce the light back and forth allowing it to stimulate many electrons before passing through one and emerging from the laser as a collimated beam. My own laser pointer has a lens that focuses the beam at a specific distance. (I know because I just lost the lens this weekend. Now I don't have a "dot" but instead I have a much larger "spot" that grows larger the further away a surface is.)

    See here for more:
  4. Nov 28, 2011 #3
    Thanks Drakkith!!! Lasers are so cool...
    I'm glad you confirm that stimulated emission is most commonly a property found only in lasers. Appreciate the info!
  5. Nov 28, 2011 #4


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    not quite ;)

    what about the MASER ?

    Microwave Amplification by the Stimulated Emission of Radiation :)


  6. Nov 28, 2011 #5

    Andy Resnick

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  7. Nov 28, 2011 #6


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  8. Nov 29, 2011 #7
    When a photon traveling along the axis of the laser tube strikes an excited atom, a second photon of the same vector and frequency is emitted. The mirrors are the feedback/gain mechanism that allows this avalanche process to continue. The front mirror also called the output coupler is not a complete mirror, and so lets some of the photons out.
    The collimation is based on the dimensions of the tube assembly, and the lasing medium.
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