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More optics

  1. Jan 7, 2006 #1
    This is probably a stupid question but I'm having a small problem with an optics issue, and it keeps coming up in past exams.

    Most of the formulae I know for things like coherence length and number of modes in a laser involve the frequency spread (linewidth) of the laser [tex] \Delta \nu [/tex]

    However the question give me the linewidth or spectral width as a wavelength e.g [tex] \Delta \lambda = 0.002 nm [/tex] along with the working wavelength [tex] \lambda = 633 nm [/tex].

    Can anyone tell me how I can get from the linewidth to the frequency spread, I've tried various things (such as dividing c by the variance etc) but can't get anything that matches the answers when I follow through.


    Incidently does anyone know an online source (or possible a good textbook) for basic non-linear optics/lasers? There have been questions on deriving equations for growth of second harmonics etc and it polarisability, and I'm lost.
  2. jcsd
  3. Jan 7, 2006 #2

    George Jones

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    What happens if you use [itex]\nu = c \lambda^{-1}[/itex] and

    [tex]\Delta \nu = \left| \frac{d \nu} {d \lambda} \right| \Delta \lambda.[/tex]

    Last edited: Jan 7, 2006
  4. Jan 7, 2006 #3
    That worked, thanks George.

    Just trying to identify and fill the gaps in my optics knowledge before my upcoming exam.

    There's a few gaps but less than I expected
  5. Jan 7, 2006 #4

    George Jones

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    Good luck!
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