Superconducting analogue of optical plasmonic waveguides

We demonstrate a direct analogy between electromagnetic properties of superconductors at frequencies up to 6 THz (superconducting gap) and plasmonic metals in the optical part of the spectrum. We also identify the existence of a surface bound mode in superconducting waveguide structures, "superconducting plasmon", that closely connected to surface plasmon polaritons in the noble metals. This is a peculiar low-frequency, low-loss mode that can be guided for tens of centimetres and confined on the scale of just few tens of nanometres, demonstrating an incredible application potential.