Spin symmetry breaking of the transverse shifts of vortex beams in surface plasmon polaritons with wave-front sensing

We have revealed the mechanism of spin symmetry breaking in the transverse shifts of vortex beams upon reflection from a waveguide structure of surface plasmon polaritons with wave-front sensing (SPP-WFS). It is shown that the spin symmetry breaking of the transverse shifts can be flexibly controlled by the polarization state and the intrinsic orbital angular momentum. Moreover, we have clearly shown a physical picture of the simultaneous occurrence of a large transverse spin splitting and perfect spin symmetry (i.e., the disappearance of the spin symmetry breaking). More importantly, we have established a close connection between the transverse symmetric spin splitting and the spin symmetry breaking of the transverse shifts. These findings provide a new pathway for advancing applications of spin-orbit optics.