Dual‐Polarization Huge Photonic Spin Hall Shift and Super‐Subwavelength Detecting Based on Topological Singularities in 1D Photonic Crystals.

Although light‐matter interaction and topology of photonic systems have been extensively studied, the topology induced novel light‐matter interaction phenomena in deep‐subwavelength region remain unexplored. Here, based on the non‐trivial topological singularity of 1D photonic crystals (PhCs), novel photonic spin Hall effects and abnormal beam behaviors are revealed in deep‐subwavelength region for the beams with nearly normal incidence, which beyond effective medium theory. The huge photonic spin Hall shift (PSHS) is observed around the singularity in the deep‐subwavelength region. The shape of reflected beam undergoes dramatic changes near the singularity, especially at the singularity, the reflected field is split as dipole‐like distribution for both polarizations. Physically, such a phenomenon is resulted from the destructive interference between the spin‐maintained beam and spin‐flipped beam. Based on these theoretical researches, super‐subwavelength thickness detecting, in which the wavelength is six orders of magnitude larger than the detecting scale, can be designed. Such sensitive detecting can also be applied to dielectric permittivity of PhC and background. Further more, by tuning the distance between two singularities in the deep‐subwavelength region, multi‐frequency channels sensitive detection and broadband platform with huge PSHS can be achieved. This system could be a platform to explore nontrivial light‐mater interaction in deep‐subwavelength region and to design of extremely sensitive detection devices. [ABSTRACT FROM AUTHOR]