Maximal spontaneous photon emission and energy loss from free electrons
By Yi Yang, Aviram Massuda, C. Roques-Carmes, S. Kooi, T. Christensen, Steven G. Johnson, John D. Joannopoulos, O. Miller, Ido Kaminer, Marin Soljačić. Nature Physics, 2018
139 citations recorded by the source corpus.
Free-electron radiation such as Cerenkov1, Smith–Purcell2 and transition radiation3,4 can be greatly affected by structured optical environments, as has been demonstrated in a variety of polaritonic5,6, photonic-crystal7 and metamaterial8–10 systems. However, the amount of radiation that can ultimately be extracted from free electrons near an arbitrary material structure has remained elusive. Here we derive a fundamental upper limit to the spontaneous photon emission and energy loss of free electrons, regardless of geometry, which illuminates the effects of material properties and electron velocities. We obtain experimental evidence for our theory with quantitative measurements of Smith–Purcell radiation. Our framework allows us to make two predictions. One is a new regime of radiation operation—at subwavelength separations, slower (non-relativistic) electrons can achieve stronger radiation than fast (relativistic) electrons. The other is a divergence of the emission probability in the limit of lossless materials. We further reveal that such divergences can be approached by coupling free electrons to photonic bound states in the continuum11–13. Our findings suggest that compact and efficient free-electron radiation sources from microwaves to the soft X-ray regime may be achievable without requiring ultrahigh accelerating voltages.Calculating the amount of radiation that can ultimately be extracted from free electrons near an arbitrary material structure is a challenge. Now, an upper limit to the spontaneous photon emission of electrons is demonstrated, regardless of geometry.
Subfields: Atomic and Molecular Physics, and Optics, Biomedical Engineering, Condensed Matter Physics
View Paper: https://www.semanticscholar.org/paper/0691203a7e0d10e12fb8a71a5a113c90536f0c90
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In Atomic and Molecular Physics, and Optics
In Biomedical Engineering
Citations in the corpus
- Applications of bound states in the continuum in photonics (2023, background): “In addition to the research areas discussed here, BICs have also drawn attention in fields such as topological acoustics 228,233,276,277 , free-electron–light interactions 278,279 , wireless power transfer 280,281 ,”