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Unidirectional launching and elongating propagation of airy surface plasmon polaritons by a metasurface coupling grating

Plasmonic metasurfaces can be used to control light wavefronts with subwavelength resolution by introducing spatial variations in the optical response of metallic antennas. Here, by taking advantage of Airy surface plasmon polaritons (Airy SPPs) with an ultralong effective propagation distance, we change their coupling grating structures into their plasmonic metasurface analogues, i.e., we introduce T-shaped nano-slits as geometric phase units to replace the conventional grating. Through the metasurface coupling grating, the propagation direction of Airy SPPs can be controlled by selecting the polarization of the excitation light. Furthermore, constructive interference effect occurs by controlling the meeting between two Airy SPPs in two structures, which continues to elongate their effective propagation distance. Effectively exploiting SPP energy and manipulating its propagation could pave the way for ultra-efficient flat optical devices.