Generation and manipulation of ultrahigh order plasmon resonances in visible and near-infrared region.

Optical properties of periodic nanorings with built-in V-shaped nanowedges (NRBV) are investigated theoretically. Tunable ultrahigh order Fano resonances are achieved and they are found to be sensitive to geometric parameters and surrounding dielectric environment of the planar nanostructure. High order Fano resonances can be suppressed or enhanced by adjusting the opening angle of the nanowedge, the size of the nanoring and the aspect ratio of the nanowedge. Moreover, manipulating the offset of the built-in nanowedge, or filling dielectrics asymmetrically can revive suppressed Fano resonances when the V-shaped nanowedge develops into a straight nanorod. Meanwhile, stronger plasmon resonances emerge alternately in the two parts of this planar nanostructure. This periodic plasmonic nanostructure produces ultrahigh order plasmon resonances and stronger electric field enhancement, which have great potential applications in multi-wavelength surface enhanced spectroscopy and biochemical sensing.