What is the significance of coupling in surface plasmons and plasmon polaritons?

[Avardia]

Hi,

I have come across the word coupling a few times looking at surface plasmons and surface plasmon polaritons. I was wondering if anyone could give me a better understanding of what it means for something like a photon to couple to a plasmons to creating a plasmon polariton. From what I'm reading it's this coupling which confines the photon to subwavelength volumes so coupling must be something considerable. This may be a very specific case but if you have answer that is more general about what coupling is I'd more than happy to receive that too.

Thank you

 

[tech99]

No one answered. In classical terms, if a wave strikes a metal at an angle to the normal, some of the incident energy is reflected, some propagates into the metal where it is dissipated and some excites a surface wave, which then propagates across the surface. I presume that surface plasmons are associated with local surface currents, part of the reflection process. The surface plasmon polaritons are presumably the electron movements associated with the surface wave as it propagates across the surface. The coupling would presumably refer to the portion of incident power ending up in the surface wave.