Plasmonic Radiation from Spin‐Momentum Locking

Chiral 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 b...

Full description

Saved in:
Bibliographic Details
Published in:Advanced science 2024-10, Vol.11 (40), p.e2406089-n/a
Main Authors: Lei, Yu‐Lu, Zhu, Juan‐Feng, Zhang, Zi‐Wen, Yang, Ji‐Tao, Zhang, Feng, Chen, Hong‐Sheng, Du, Chao‐Hai
Format: Article
Language:English
Subjects:
Bandwidths
chirality
Electric fields
free‐electron radiation
Propagation
Quantum dots
Radiation
spin‐momentum locking
spoof surface plasmons
Citations: Items that this one cites
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Chiral 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. This study presents a novel method for chiral free‐electron radiation by leveraging spin‐momentum locking (SML) in spoof surface plasmons (SSPs). Through phase‐matching, moving electrons excite SSPs along the modified structure, thus diffracted into Smith‐Purcell radiation (SPR). This approach yields tunable chiral SPR with extensive polarization control and frequency tunability, representing a significant advancement toward achieving near‐unity chiral radiation.
ISSN:2198-3844
2198-3844
DOI:10.1002/advs.202406089