Time response of fluorescence-like emissions in silica-based optical fibers

Abstract In silica-based optical fibers, the time response is measured of what we have called before the fluorescence-like emission around 385–415, 430–450, and 630–690 nm when the pump is at 532 nm. The results show that the time widths are always of the same order as that of the pump, i.e. a few tens of picoseconds. The time delays indicate that the emission originates from the input end of the fiber. The fact that the blue-uv lines lie always within a fluorescent region indicates a multiphoton absorption process populating a high energy level of defect states. Finally, we suggest the amplication of a four-wave mixing produced in the region close to the injection point.