Affiliation:
1. Center for Carbon‐based Electronics School of Electronics Peking University Beijing 100871 China
2. State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Beijing 100871 China
3. Science, Mathematics, and Technology (SMT) Singapore University of Technology and Design 8 Somapah Road Singapore 487372 Singapore
4. Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China
Abstract
AbstractChiral light emission plays a key role in sensing, tomography, quantum communication, among others. Whereas, achieving highly pure, tunable chirality emission across a broad spectrum currently presents significant challenges. Free‐electron radiation emerges as a promising solution to surpass these barriers, especially in hard‐to‐reach regimes. Here, chiral free‐electron radiation is presented by exploiting the spin‐momentum locking (SML) property of spoof surface plasmons (SSPs). When the phase velocity of free electrons matches that of the SSPs, the SSPs can be excited. By implementing wavenumber compensation through perturbations, the confined SSPs are transformed into free‐space free‐electron radiation. Owing to the law of angular momentum conservation, this process converts the transverse spin angular momentum of SSPs into the longitudinal spin angular momentum of free‐electron radiation during the process, producing pure, tunable, and chiral free‐electron radiation across a broad spectrum. This method achieves an optimal degree of circular polarization approaching −1. The innovative methodology can be adapted to SML‐enabled guided states or silicon photonics platforms, offering new avenues for achieving chiral emission.
Funder
National Natural Science Foundation of China
National Key Research and Development Program of China