Dynamic tailoring of an optical skyrmion lattice in surface plasmon polaritons.

A skyrmion is a topologically protected soliton with a spin structure on the micro/nano scale that has promising applications in magnetic information storage and spintronics devices. This study focuses on the optical skyrmion lattice structures created in the surface plasmon polaritons (SPPs) field. Both the Néel-type optical skyrmion lattice formed by the electric field vector and Bloch-type optical skyrmion lattice formed by the magnetic field vector are generated via exciting a hexagonal grating structure on the metal surface with six Gaussian optical spots. Such a multiple-spot excitation can be realized through tightly focusing a specially designed complex field with a high NA lens. Through introducing the phase difference of the excitation beams to shift the SPP standing waves, the shape and position of the optical skyrmion lattice can be dynamically controlled. Both the electric field vector and magnetic field vector are evaluated quantitatively based on the electric and magnetic field obtained by finite difference time domain (FDTD) simulation to demonstrate the validity and capability of the proposed technique.