Abstract: Using TEOS, YbCl₃, AlCl₃ as precursors, Al³⁺, Yb³⁺ co-doped silica fiber core glass was fabricated by Sol-Gel method. ICP-AES tests showed that the compositions of the gel derived from base catalyzed sol were not uniform. The composition inhomogeneity of the gel was eliminated by acid catalyzed sol. The Al³⁺, Yb³⁺ co-doped silica core glass with 2.5 mm in diameter and 50 mm in length was obtained after heat-treatment, melting and polishing. The absorption, infrared transmission and fluorescence spectra were measured with glass slice at 2 mm thickness. The fluorescent lifetime centered at 1020 nm was 896 μs, and the Hydroxyl radical (-OH) content was 0.4×10^-6. The glass structures from acid and base catalyzed sols were analyzed by micro Raman spectroscope. Fiber preform was fabricated by rod-in-tube technique with the obtained core glass. The Al³⁺, Yb³⁺ co-doped single cladding silica fiber was drawn at 2000℃. Its optical homogeneity was evaluated by the refractive index profiler. Refractive index difference (Δn) in fiber core area was less than 2×10^-4. This work can supply homogeneous and large size core glass for large mode PCF and large mode cladding fiber. And it can provide reference for preparation of homogeneous multi-component optical material by the Sol-Gel method.

Key words: Sol-Gel method, SiO₂ powder, homogeneity, Yb³⁺,Al³⁺ co-doped silica glass fiber core, spectroscopic properties of Yb³⁺ ion