1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Converting laser fwhm bandwidth in m to hz

  1. Apr 9, 2010 #1
    hi, pls can someone help me with converting FWHM bandwidth of a laser from metres to hertz
  2. jcsd
  3. Apr 9, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Just from the dimensions
    frequency (1/s)= speed (m/s) / wavelength (m)
  4. Apr 9, 2010 #3
    thank you but i didn't think you could directly convert fwhm bandwidth just using that, when i did it i got a bandwidth of region 10E17 Hz -does that seem a bit high from a ruby laser cavity length 0.1m?

    If i post the whole question it might help. Also should i include the refractive index of the medium ie c/n=f lambda, if this is the right way to do it?

    for the 0.1m cavity, n =1.8, FWHM gain bandwidth is 2E-9m
    qu is: what is the longitudinal mode spacing and the number of lasing modes? i could give the spacing in either freq or wavelength but its easier to do i think in freq that's why i wanted to convert. many thanks if you can help.
  5. Apr 10, 2010 #4
    you can use the following formula

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook