New optical system decodes phase and polarization charges in one measurement

Researchers at the University of Science and Technology of China have demonstrated a dynamic way to detect both phase and polarization topological charges in Poincaré beams at once. The approach could improve how complex light fields are measured for optical communications and other fast-changing applications.

Why it matters: - Structured light fields are becoming more complex, and existing measurement tools often capture only one property at a time. - The new approach can detect phase and polarization topological charges simultaneously in a single measurement. - That makes it more practical for dynamic optical fields used in high-speed communications and quantum information processing. - The method also reduces mode crosstalk, which supports higher detection accuracy.

What happened: - A research team led by Professor Anting Wang at the University of Science and Technology of China proposed and experimentally verified a system for dynamic detection of arbitrary Poincaré beams. - The system uses the spin-dependent response of Pancharatnam-Berry optical elements, or PBOEs, to decode topological charges. - The paper was made available online on March 30, 2026 and published in Volume 2 of Opto-Electronics Plus on the same date. - The paper is titled “Simultaneous Dynamic Detection of Phase and Polarization Topological Charges of Poincaré Beams.”

The details: - The core setup uses a pair of conjugate-designed PBOEs that perform a log-polar coordinate conformal optical transformation. - A Beam Switcher generates switchable Poincaré beams as the incident light. - The orthogonal eigenstates {R, L} are spatially expanded into two vertically aligned rectangular beams by PBOE1. - PBOE2 applies phase correction before the beams are output. - A cylindrical lens converts the topological information of the orthogonal eigenstates into one-dimensional transverse spatial shifts in the focal plane. - The Beam Switcher uses spin-to-orbital angular momentum conversion from two Q-plates to modulate the beam’s phase and polarization. - The setup supports flexible switching of Poincaré beams between output states on the hybrid-order Poincaré sphere and the high-order Poincaré sphere. - The system separates the orthogonal eigenstates of arbitrary Poincaré beams and decodes different combinations of phase and polarization topological charges in one measurement. - The output intensities of the orthogonal components naturally separate in the image plane after focusing. - The separation mechanism helps avoid crosstalk.

Between the lines: - The design addresses a core limitation of older methods: interferometry measures phase only and needs a stable reference beam, while Stokes parameter analysis measures polarization only and requires frequent optical adjustment. - The paper frames the approach as a cleaner physical route to multidimensional light-field measurement rather than a patchwork of separate tests. - The work also points to a receiver architecture that could matter for practical optical communication systems. - The research was supported by the National Natural Science Foundation of China under grant 62375251 and the National Key Research and Development Program of China under grant 2020YFB2205802.

What's next: - The system could be adapted for practical optical communication receivers that need fast, simultaneous decoding of multiple light-field parameters. - The team’s broader work in laser technology, vortex optical fields, and advanced displays suggests further applications for structured-light measurement and control. - The research group says it has published more than 130 papers and filed 47 invention patents, with 26 authorized, plus 28 authorized utility model patents and 8 completed technology transfers. - Professor Wang also authored the monograph “Optoelectronic Technology” and has received teaching awards from the Chinese Academy of Sciences and Anhui Province.

The bottom line: - The new PBOE-based system turns complex structured light into directly readable spatial shifts, enabling one-shot detection of both phase and polarization topological charges.