Chiral-defect mediated transmitted spin Hall effect in one-dimensional photonic crystals

Abstract We propose and theoretically investigate a chiral-defect-enabled transmitted photonic spin Hall effect in a symmetric one-dimensional photonic crystal (1DPC) of the form ( A B ) N C ( B A ) N , where A and B are isotropic dielectrics and C is an isotropic chiral defect layer. Using a helicity-resolved transfer-matrix formalism together with a Gaussian-beam stationary-phase analysis, we show that the chiral defect lifts the degeneracy of the defect cavity mode into spectrally separated right- and left-circularly polarized resonances over a wide range of incidence angles. Near these helicity-split tunneling resonances, the transmission phases exhibit ultra-steep angular dispersion, which produces giant spin-dependent beam displacements in the forward channel while maintaining high throughput. For optimized parameters, the normalized spin-dependent displacement reaches the order of 10 4 in units of the operating wavelength with transmittance exceeding 0.5. We further demonstrate deterministic tuning and sign reversal of the transmitted spin splitting. These results establish chiral-defect 1DPCs as a compact platform for spin-controlled beam routing, in-line spatial demultiplexing, and polarization-resolved sensing based on lateral-shift readout.