Light induced by charged particles in optical fibers

The field of a charged particle passing through or near an optical fiber polarizes the fiber atoms transiently. This produces a particle-induced guided light (PIGL). PIGL can also be assisted by a metallic object stuck to the fiber, via plasmon excitation. Type-I PIGL is produced in a translation-invariant part of the fiber, type-II PIGL is produced at a fiber end, an indentation or a metallic object.Properties of type-I PIGL in a single-mode fiber (spectrum, polarization) are reviewed. Order of magnitudes are given for type-II PIGL from a fiber end or a metallic ball. Interference effects are outlined, in particular the guided Smith–Purcell radiation.Applications of PIGL to beam diagnostics are discussed.