Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Reflected wave at complex refrective index

  1. Sep 8, 2011 #1
    A plane wave can be described by the real part of the exponential wave equation:


    Adding the subscript i or r for incident or reflected waves, the ratio of the amplitude of reflected to incident wave is given by:

    [tex]\frac{E_{r0}}{E_{i0}} = \frac{n_1-n_2}{n_1+n_2}[/tex]

    But if n2 is complex, then this leads to a complex Er0. What does this mean for the physical wave, the real part of E?


    To me it looks like 2 out of phase waves are reflected. If this is right can you point me somewhere I can read up more about it? Or have I abused some notation somewhere?

    Thanks for your help understanding whats going on.
  2. jcsd
  3. Sep 8, 2011 #2


    User Avatar
    Science Advisor

    No, as you said, you have to take the real part of E, only. A complex E_0 can be writen as [itex] |E_0|\exp(i\phi)[/itex]. Hence the reflected wave will be out of phase with the incident one.
    For non-perpendicular incidence this leads to the reflected wave becoming partly circularly polarized and is used in elipsometry.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook