Topology transfer from vortex electrons to structured radiation via guided Cherenkov emission: orbital angular momentum and polarization skyrmions

Sun-Hong Min,  Matlabjon Sattorov,  Dongpyo Hong,  Jin Pyung Kim,  Ohjoon Kwon,  Ilsung Cho,  Seonmyeong Kim,  Inkeun Baek,  Seunghyuk Park,  Young Joon Yoo,  Sang Yoon Park*

<Abstract>

A topology-transfer interface from vortex electrons to structured electromagnetic radiation is experimentally realized in the 15–25 GHz microwave/millimeter-wave regime, enabling simultaneous readout of orbital and polarization topology. Guided Cherenkov emission in an all-metal slow-wave structure maps the prepared vortex-electron charge ℓe onto the radiated-field orbital angular momentum content, with the intensity-weighted mean<ℓ>following ℓe and Var(ℓ) quantifying residual modal broadening. The transfer is validated by off-axis fork-hologram interferometry, phase-retrieval modal decomposition, and q-plate analysis of the helicity-resolved shift Δℓ ≈ 2. Full-Stokes polarimetry reconstructs the vector field and yields a cumulative skyrmion number approaching unity within a fixed analysis window. The measured angle-frequency distributions follow guided Frank-Tamm kinematics and agree with Cherenkov selection rules for vortex beams. Although the present implementation is performed in the GHz regime, the mechanism is governed by guided dispersion and phase matching rather than by a specific spectral band. These results establish guided Cherenkov emission as an electron-to-field topology-transfer platform for structured-radiation generation, with implications for structured-light photonics, simultaneous scalar and vectorial topology readout, and noninvasive diagnosis of vortex-electron states.

DOI: 10.29026/oea.2026.260107