Interferometric vortex polarimetry: achieved by intrinsic OAM generation and common-path interference.

This work proposes the Embedded Interferometric Vortex Polarimetry (E-IVP), a technique that breaks the 'generate-first, interfere-later' scheme in interference-based polarimetry. Its basic concept is to utilize the intrinsic spin-to-orbital angular momentum conversion of vortex retarders to generate orthogonal OAM channels in a single beam, forming a compact common-path self-reference vortex interferometer without an external reference beam or additional optical components. This scheme avoids mechanical rotation and simplifies alignment, enabling single-shot and simultaneous retrieval of polarization parameters. Birefringence experiments confirm its performance. Notably, the proposed scheme exhibits strong extensibility: higher-order vortex retarders enable additional OAM channels, potentially supporting more complex polarization measurement (e.g., Mueller matrix) and broader sensing applications.