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Homework Help: High Power Pulse Propagating Through a Medium

  1. May 12, 2015 #1
    1. The problem statement, all variables and given/known data

    I have been given this problem but I don't think I'm doing it right as I have just disregarded n0?

    Calculate the maximum length of material (nonlinear refractive index n2=2.5×10-19 cm2W-1) that can be traversed if the total accumulated phase difference between the beam centre (Intensity I =1×1011Wcm-2 , wavelength λ=1053nm) and the beam edge (I=0) is to be less than 2 rad.

    2. Relevant equations
    n = n0 + n2I

    2πnL/λ = nkL

    Φ(x) = n k L(x)

    3. The attempt at a solution

    I just combined the equations to get Φ = 2π/λ * (n0 + n2I)L

    and put the numbers in but let n0 equal 1

    So my answer was L = 3.35x10-7cm

    I don't even know if I've used the right equations so help would be much appreciated
  2. jcsd
  3. May 12, 2015 #2


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    What is the expression for the phase difference between the beam center and beam edge at any distance?
  4. May 12, 2015 #3
    I think you mean the B integral?

    B = ∫n2I(z)dz
  5. May 12, 2015 #4


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    Not exactly, although you can still get the sense of what I meant out of the B integral.
    Just the expression of the difference between phases in two different locations across the beam's cross-section (fixed distance) which is needed to answer your question, so that you indeed are not required to know n0.
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