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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
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