Modified weak measurement model of the photonic spin Hall effect including cross-polarization coefficients

Abstract The photonic spin Hall effect (PSHE) is highly sensitive to the interface properties, making it a powerful tool for characterizing film material parameters. However, existing weak measurement models, which neglected cross-polarization coefficients, are inadequate for analyzing the properties of optical anisotropic films and their strain modulation characteristics. This limitation stems from the fact that strain modulation primarily affects the cross-polarization coefficients of films, but has a negligible impact on the conventional Fresnel coefficients, thereby significantly reducing the model’s resolution limit under small strain conditions. To address this issue, a modified model for PSHE beam splitting and weak measurement, exhibiting broader applicability to both in-plane and out-of-plane shifts, was established in the paper. It applies not only in scenarios with arbitrary linear polarization in both the pre-selection and post-selection states, but also in the cases of involving absorptive media characterized by a surface photoconductivity tensor such as weyl semimetals(WSM), thereby allowing for the analysis of their reciprocal and non-reciprocal characteristics. Subsequently, the simulation method was employed to analyze the PSHE shifts of WSM under strain modulation, and the results were compared with the models that did not include the cross-polarization coefficient. The comparison results demonstrate that, whereas the model lacking the cross-polarization coefficient produces only a 0.7° shift, the modified model transforms the 1% compressive strain into a significant 27.6° sign reversal position shift.