Coherent Light induced in Optical Fiber by a Charged Particle

11th International Symposium on Radiation from Relativistic Electrons in Periodic Structures

Artru, Xavier^1,2 ; Ray, Cédric^1,3

Université de Lyon, Université Lyon 1, Villeurbanne

F-69622, France^1

Institut de Physique Nucléaire de Lyon, CNRS-IN2P3, France^2

Institut Lumière Matière, Université Lyon 1, France^3

关键词: Background light;    Grazing incidence;    Longitudinal momentum;    Microscopic points;    Plasmon excitations;    Reciprocity theorem;    Relative velocity;    Smith-Purcell radiations;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/732/1/012005/pdf
DOI  :  10.1088/1742-6596/732/1/012005

来源: IOP

【 摘 要 】

Coherent light production in an optical fiber by a charged particle (named PIGL, for particle-induced guided, light) is reviewed. From the microscopic point of view, light is emitted by transient electric dipoles induced in the fiber medium by the Coulomb field of the particle. The phenomenon can also considered as the capture of virtual photons of the particle field by the fiber. Two types of captures are distinguished. Type-I takes place in a uniform part of the fiber; then the photon keeps its longitudinal momentum pz. Type-II takes place near an end or in a non-uniform part of the fiber; then pzis not conserved. Type-I PIGL is not affected by background lights external to the fiber. At grazing incidence it becomes nearly monochromatic. Its circular polarization depends on the angular momentum of the particle about the fiber and on the relative velocity between the particle and the guided wave. A general formula for the yield of Type-II radiation, based on the reciprocity theorem, is proposed. This radiation can be assisted by metallic objects stuck to the fiber, via plasmon excitation. A periodic structure leads to a guided Smith-Purcell radiation. Applications of PIGL in beam diagnostics are considered.