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Is laser light polarized or unpolarized?

  1. Dec 31, 2008 #1
    Hi all,

    I understand laser to be monochromatic (i.e. single frequency) and coherent (i.e. all the waves are in phase with each other.)

    My question is : is laser a form of polarized light too? In other words, can the electric field be in almost all possible plane directions, or is it just limited to just one plane?

    Pls advise. Thanks. Happy new year.
  2. jcsd
  3. Dec 31, 2008 #2

    Andy Resnick

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    Laser light is polarized due to the use of a 'Brewster window' which acts as both mirror and output. Some laser light is more polarized than others- gas lasers and Nd:YAGs are highly (linearly) polarized, while diode lasers are much less and may even be elliptically polarized. VCSELs can have very non-classical states, like radial and tangential polarization.
  4. Jan 1, 2009 #3
    Thanks andy!
  5. Dec 23, 2010 #4
    It is a common mistake to think that laser light is always polarized, but this is not the case.
    All lasers involve some kind of a resonator which causes a mode competition between different modes and also polarizations, in which the least lossy mode lases. In the same way that there exists multi-mode lasers, in which several spatial modes are lasing, there is generally no prohibition on unpolarized lasing.
    Further more, not all lasers involve a Brewster window...
    Please notice the following links:

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