Modulation of the type and excitation region of plasmonic topological quasiparticles in a metasurface by tailoring the excitation light

We propose and demonstrate to manipulate the generation of plasmonic skyrmion and meron as well as their field spatial distribution with a metasurface composed of T-shaped nanoslit arrays by tuning the wavelength and spin of the excitation light. Simulation results show that plasmonic skyrmion and meron can be constructed and their field distribution can be manipulated within the proposed metasurface. Controllable unidirectional propagation of surface plasmon polaritons, which depends on the wavelength and spin of the incident circularly polarized light via the geometric phase introduced by the T-shaped nanoslit array, supports the formation of plasmonic topological quasiparticles. Scanning near-field optical microscope (SNOM) is employed to image the field profile of the plasmonic topological quasiparticles under the different excitation conditions, and it is found out that the field profile obtained by SNOM is in good agreement with the simulation result.