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

How one should excite Surface Plasmon Polaritons on a prism?

  1. Jun 18, 2011 #1
    I've got a red laser, goniometer for aligning the angles, photoreceptor that outputs values...

    I've got a right angle prism with a ~40nm gold coating on the diagonal, and I *should* be getting some sort of dip in the intensity at certain angles, as P-polarized EM waves should be absorbed into SPP resonance, but I am not getting this intensity dip at all. I'm using the Kretschmann configuration for this experiment. The laser is in the red part of the spectrum.

    I have a few possible leads, but which ones do you think would be a waste of time to correct, or which one do you think I should look at first?

    1: Prism isn't perfectly smooth and polished
    2: The alignment of the laser isn't 100% exactly in the center of the photoreceptor aperture, which is an order of magnitude larger in radius than the laser dot
    3: There was mild ambient light in the room where the measurements were taking place (lights were off, though)
    4: Some possible slight 1-2 degree offset in rotation on an axis normal to the prism's diagonal
    5: The dip that causes SPP resonance is immeasurably small, given the power of the laser, and the sensitivity of the photoreceptor
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?