Cherenkov Radiation at Speeds Below the Light Threshold: Phonon-Assisted Phase Matching
- 26 January 2001
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 291 (5504) , 627-630
- https://doi.org/10.1126/science.291.5504.627
Abstract
Charged particles traveling through matter at speeds larger than the phase velocity of light in the medium emit Cherenkov radiation. Calculations reveal that a given angle of the radiation conical wavefront is associated with two velocities, one above and one below a certain speed threshold. Emission at subluminal but not superluminal speeds is predicted and verified experimentally for relativistic dipoles generated with an optical method based on subpicosecond pulses moving in a nonlinear medium. The dipolar Cherenkov field, in the range of infrared-active phonons, is identical to that of phonon polaritons produced by impulsive laser excitation.Keywords
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