Enhanced opposite Imbert–Fedorov shifts of vortex beams for precise sensing of temperature and thickness

Imbert–Fedorov (IF) shift, which refers to a tiny transverse splitting induced by spin-orbit interaction at a reflection/refraction interface, is sensitive to the refractive index of a medium and momentum state of incident light. Most of studies have focused on the shift for an incident light beam with a spin angular momentum (SAM) i.e., circular polarization. Compared to SAM, orbital angular momentum (OAM) has infinite dimensions in theory as a new degree of freedom of light and plays an important role in light-matter coupling. We demonstrate experimentally that the relative IF shifts of vortex beams with large, opposite OAMs are highly enhanced in resonant structures when light refracts through a double-prism structure (DPS). In this configuration, the precision sensing of the air gap’s thickness and temperature is achieved through the observation of these enhanced relative IF shifts. Notably, the sensitivity to both thickness and temperature increase proportionally with the absolute value of opposite OAMs. Our results offer a robust technological platform for practical applications in sensing of thickness and temperature, ingredients of environment gas, spatial displacement, chemical substances and structural deformation.