Structural Analysis Of Optical Fiber Preforms Using Raman Microprobe

We have investigated the incorporation of aluminum and phosphorus into vitreous silica using a Raman microprobe. By studying bulk glasses of varying Al/P ratio we have identified the presence of different structural units in the glass and used these to analyze radially their distribution in optical fiber preforms. Our analysis has shown the presence of P=0 and AlPo4-like structures, whose relative concentration depends on glass composition. In addition, the results give evidence for both phosphorus and aluminum diffusion in optical fiber preforms prepared by MCVD.