Comparative studies on large-core-energy fibres with silica core and fluorine-doped cladding

Different standard commercial optical fibre samples (silica core with fluorine-doped cladding) were prepared by a modified chemical vapour deposition (MCVD) technique. Their surface and cross-section morphology were characterized by scanning electron microscopy (SEM). Further, X-ray photoelectron spectroscopy (XPS) was used to characterize the compositions, and the chemical environment was also explored by investigating the chemical elements in the samples. The cladding fluorine content for the three fibres is 3.16 wt%, 2.16 wt%, and 1.85 wt% (for fibres A, B, and C, respectively). Moreover, the surface became smoother. Further, the fibre transmission loss corresponding to the fluorine content of 3.16 wt%, 2.16 wt%, and 1.85 wt% was 3.6dB/km, 2.830dB/km, and 2dB/km, respectively. These results indicate that the transmission loss decreases with decreasing fluorine content; thus, fluorine doping affects the optical glass fibre microstructure and transmission loss.