TIME RESPONSE OF FLUORESCENCE-LIKE EMISSIONS IN SILICA-BASED OPTICAL FIBERS

In silica-based optical fibers, the time response is measured of what we have called before the fluorescence-like emission around 385-415, 4 30-450, and 630-690 nm when the pump is at 532 nm. The results show th at 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 emiss ion originates from the input end of the fiber. The fact that the blue -uv lines lie always within a fluorescent region indicates a multiphot on absorption process populating a high energy level of defect states. Finally, we suggest the amplification of a four-wave mixing produced in the region close to the injection point.