Year: 2026
Type: article
Abstract: The Smith–Purcell effect arises when charged particles move near a periodic structure, emitting radiation. Conventional approaches for generating chiral Smith–Purcell radiation rely on metasurface phase engineering or resonant mode interference, typically producing narrow-band, weakly chiral emission. Here, we introduce a resonance-interference-free mechanism that leverages the properties of the charged particles themselves. Using a non-chiral, non-resonant silicon grating, we demonstrate broadband, tunable Smith–Purcell radiation with high chirality, achieving a record-high degree of polarization of 0.87. This is enabled by converting the transverse spin angular momentum of electron-induced evanescent waves into a longitudinal form, producing opposite chirality at different azimuthal angles. Beam twisting or displacement offers precise control over chirality, paving the way for compact chiral light sources, advanced X-ray imaging, and integrated particle diagnostics platforms. Existing approaches for generating chiral Smith–Purcell radiation remain limited. Here, the authors overcome these limitations by uncovering the inherent chirality of the Smith–Purcell effect using non-chiral, non-resonant silicon gratings. By controlling the electron–grating configuration, this chirality can be selectively manipulated to produce tunable and highly chiral polarized radiation.
Source: Nature Communications
Institutions: Singapore University of Technology and Design, Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, Nanjing University, Agency for Science, Technology and Research, Institute of Advanced Intelligence and Computing, Institute of Materials Research and Engineering, National University of Singapore, Suzhou Research Institute
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $6,990
Funders: National Research Foundation, Agency for Science, Technology and Research, National University of Singapore, National Research Foundation Singapore, Ministry of Education - Singapore, National Natural Science Foundation of China, Harbin Institute of Technology, Ministry of Education, India, Henan University, Singapore University of Technology and Design, Peking University, National Key Research and Development Program of China
Awards: G1111047385, G1722296525, G1822449344, G1983431784, G2952235266, G3316082199, G3655309238, G4052554125, G4197854740, G4444807105, G506366594, G5262486799, G5644644331, G5942131513, G6085284823, G6380015898, G6447473835, G6836036477, G685581956, G7539855103, G7572826488, G8002597874, G8601039191, G8773752900
OpenAlex ID: W7162497965