Control of defects in optical fibers-a study using cathodoluminescence spectroscopy

Cathodoluminescence spectra of germanosilicate and silicate glass in modified chemical vapor deposition (MCVD) and vapor-phase axial deposition (VAD) preforms are presented, and the influence of co-doping with phosphorus, boron, and fluorine on the peaks associated with the E' and the so-called drawing-induced defects are studied. A simple reaction scheme is developed which illustrates that these defects can be controlled by the electron donor (P) and scavenger (B,F) properties of the co-dopant.>