| 摘要 |
PURPOSE:To obtain the title optical fiber, capable of producing nonlinear effects, such as fiber Raman laser, etc., with a high efficiency, having extremely low loss and high Raman scattering coefficient and excellent in strength, by forming a core from (F-added) GeO2, the first clad from the F-added GeO2 and the second clad from SiO2 glass-added GeO2. CONSTITUTION:A raw material gas consisting of GeCl4 transported by Ar gas and, as necessary, GeF4 is subjected to hydrolytic reaction in a flame formed from O2, H2, Ar, etc., at the lower end of a supporting rod 4 rotated by a driving unit 5, e.g., at about 20r.p.m. number of revolutions in a reaction vessel 7 using a torch 1 to form fine (F-added) GeO2 glass particles and afford a porous perform 8 for a core. The resultant preform is then pulled up according to the growth rate thereof an d the GeCl4 and GeF4 are subjected to hydrolytic reaction in a flame in the same manner as described above with a torch a to form a porous preform 9 consisting of F-added GeO2 fine glass particles for the first clad. The GeCl4 and SiCl4 are then subjected to hydrolytic reaction in a flame in the same manner using a torch 3 to form a porous preform 10 consisting of SiO2-added GeO2 for the second clad. The resultant preform is subsequently heated, dehydrated and transparentized. |
