Plasmon switching: observation of dynamic surface plasmon steering by selective mode excitation in a subwavelength slit

S. B. Raghunathan (1) , Choon How Gan (2, 3) , T. van Dijk (4) , Buntha Ea-Kim (2) , H. F. Schouten (4) , W. Ubachs (4) , Philippe Lalanne (5) , T. D. Visser (1, 4)

1 Department of Electrical Engineering
2 Laboratoire Charles Fabry / Naphel
3 Electronic and Photonics Department
4 Department of Physcis and Astronomy
5 lp2n-03,lp2n-13

We report a plasmon steering method that enables us to dynamically control the direction of surface plasmons generated by a two-mode slit in a thin metal film. By varying the phase between different coherent beams that are incident on the slit, individual waveguide modes are excited. Different linear combinations of the two modes lead to different diffracted fields at the exit of the slit. As a result, the direction in which surface plasmons are launched can be controlled. Experiments confirm that it is possible to distribute an approximately constant surface plasmon intensity in any desired proportion over the two launching directions. We also find that the anti-symmetric mode generates surface plasmons more efficiently than the fundamental symmetric mode.

Domaines: Optique / photonique; Optique [physics.optics]

S. B. Raghunathan, Choon How Gan, T. van Dijk, Buntha Ea-Kim, H. F. Schouten, et al.. Plasmon switching: observation of dynamic surface plasmon steering by selective mode excitation in a subwavelength slit. Optics Express, 2012, 20 (14), pp.15326-15335. ⟨hal-00812814⟩