how is the totally reflection of the laser beam from the material affect on its electric field?
Dear Amany Gouda,
the critical angle phic of total reflection is defined via:
sin(phic) = n1/n2; n2 being the refractive index of the material, which is passed by the laser beam. Outside this material we have refractive index n1 (n1 =1 for vacuum or air); phic is the angle between the laser beam and the normal to the reflecting surface.
The refractive index however is a linear (Pockels effect) or a quadratic (Kerr effect) function of the electric field E.
For details please 'google' by youself and/or have a look at appropriate books/papers on electro-optics. You have got now a lot of search terms.
A main challenge dealing with this topic is the directional dependence of Laser polarization and direction of the electric field.
Good luck in your studies.
https://en.wikipedia.org/wiki/Electro-optic_effect
https://en.wikipedia.org/wiki/Pockels_effect
https://en.wikipedia.org/wiki/Kerr_effec
http://opt.zju.edu.cn/zjuopt2/upload/resources/chapter18%20Electro-Optics.pdf
Your question is not clear: you mean the influence of reflected light on laser operation (optical feedback) or something other ?
Is it CW beam? if so and it was 100% reflected than the amplitude should preserve. Polarization may or may not be modified, depends on material properties, incidence polarization state and orientation.
If in addition this is a temporal varying field then the time shape can also vary, depending on dispersion properties of the material. usually, reflected beam does not strongly interacts with the inner layers, so to the most part this modification can be assumed weak.