Perfect transverse spin splitting by a single particle with bianisotropy

Transverse spin splitting is a novel optical phenomenon which stems from the spin-orbit interaction of light. In this paper, we reveal the perfect transverse spin splitting in the scattered far-field of a single particle with bianisotropy. It is the result of the polarization twist effect caused by the omega-type bianisotropy of the structure in which the magnetic and electric fields interact in an unusual way and form a transverse spin dipole moment. Based on the dipole model, we conducted a detailed theoretical analysis of the relationship between the magnetoelectric coupling and the polarization state of the scattered far field. Our method reveals a physical mechanism of splitting the spin state of incident light which is regarded as a kind of giant spin Hall effect. Moreover, this perfect transverse spin splitting can also be understood by the separation of far-field polarization singularities. Our results provide a new platform for manipulating the spin state in the scattered far field and open an avenue for designing the spin structure.