Thin-Film Magneto-Optic Plasmonic Sensor With the Photonic Spin Hall Effect

This letter explores advanced thin-film magneto-optic plasmonic (TF-MOP) sensors that integrate the photonic spin Hall effect (PSHE) into sensing applications. The proposed structure, consisting of a BK7 prism, gold, graphene, cobalt, and air, enables ultraprecise measurement of the refractive index and magnetic field at an excitation wavelength of 633 nm in air. Our study demonstrates an exceptionally large transverse spin-dependent shift of approximately 9.15 µm, which is 11.58 times greater than that observed in a purely plasmonic structure. This significant transverse shift allows the TF-MOP sensor to function as a highly sensitive PSHE-based refractometer, achieving a remarkable sensitivity of 25 861.25 µm/RIU across a minute change in refractive index range, including air and helium.