Enlarging spin-dependent transverse displacement of surface plasmon polaritons focus

By introducing additional spin angular momentum (SAM) induced spiral phase, the spin-dependent transverse displacement of surface plasmon polaritons (SPPs) focus is effectively enlarged. The separation between the SPPs focuses generated by left circularly polarized (LCP) light and right circularly polarized (RCP) light reaches 1500 nm, which is six times larger than the previously reported values with semicircular plasmonic lens. The relationship between the displacement of the SPPs focus and the total spiral phase that consisted of the intrinsic and the additional spiral phase is theoretically established. Furthermore, the flexibility and versatility of the proposed mechanism is demonstrated by reversing or continuously controlling the SPPs focus. These findings hold great promise for spin-based plasmonic devices and the related applications, such as on-chip communication.