Fresnel Equations for a beam instead of a plane wave

  • Thread starter montealeku
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  • #1
In many books we can find the derivation of Fresnel Equations (TE and the TM reflection and transmission coefficients), but always for the case of a plane wave. How can we go about obtaining the reflection coefficient if the incident light took the form of a beam rather than a plane wave?

We may use the paraxial approximation, or we may consider the particular case of a Gaussian beam at its waist, but I cannot figure out the solution for the general case. Any help is most appreciated!
 

Answers and Replies

  • #2
Note: The question is related to Problem 6.2-3 in the Fundamentals of Photonics book, by Saleh and Teich.
 
  • #3
Could a spatial fourier transform be used? I'd really appreciate if anyone could share his/her thoughts and perhaps provide more elaboration
 
  • #4
213
8
The starting point of the fresnel equations is

[tex] \frac{1}{\mu_i v_i } (E_i-E_r) cos(\theta_i) = \frac{1}{\mu_t v_t } E_t cos(\theta_t) [/tex]

So you can derive it for any electric field you want
 
  • #6
213
8
well what is the difference between a plane wave and a beam, isn't it the electric field

And could you maybe explain your problem in more detail
 
  • #7
sgd37,

First of all, thank you for your interest in the topic and your previous replies. The question, as I mentioned above, is taken from Problem 6.2-3 in Fundamentals of Photonics, 2nd Edition, by Saleh and Teich (and no further information is provided). My undestanding is that the book author is not asking for a formal and rigorous solution (as that proposed in the article that I was suggesting), but a short explanation of how could we deal with calculating the reflection coefficient if instead of the idealized case of a plane wave we had a beam (which does not need to be Gaussian). I was thinking of a spatial fourier transform, but I am not sure... if anyone can think of a different approach, or detail a bit how to do it with the spatial fourier transform (I am not keen on the topic), it would be most appreciated.
 
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