Chromium doped nano-phase separated Yttria-Alumina-Silica glass based optical fiber preform: fabrication and characterization

Transition metal (TM) doping in silica core optical fiber is one of the research area which has been studied for long time and Chromium (Cr) doping specially attracts a lot of research interest due to their broad emission band covering U, C and L band with many potential application such as saturable absorber or broadband amplifier etc. This paper present fabrication of Cr doped nano-phase separated silica fiber within yttria-alumina-silica core glass through conventional Modified Chemical Vapor Deposition (MCVD) process coupled with solution doping technique along with different material and optical characterization. For the first time scanning electron microscope (SEM) / energy dispersive X-ray (EDX) analysis of porous soot sample and final preform has been utilized to investigate incorporation mechanism of Cr-ions with special emphasis on Cr-species evaporation at different stages of fabrication. We also report that optimized annealing condition of our fabricated preform exhibited enhanced fluorescence emission and a broad band within 550-800 nm wavelength region under pumping at 532 nm wavelength due to nano-phase restructuration.