| 摘要 |
PURPOSE:To provide a low-loss optical fiber which can maintain a transmission characteristic stable for a long period of time in a hydrogen atmosphere by using core glass added with an extremely slight amt. of an alkaline (earth) metal as a hydrogen resisting agent to form the fiber. CONSTITUTION:A clad 1b having the refractive index lower than the refractive index of a core 1a consisting of the core glass formed by adding 3-10wt% dopant such as GeCl4, POCl3 or BBr3 and 0.001-15ppm alkali metal such as Li, Na, K, Rb or Cs and/or alkaline earth metal such as Mg, Ca, Sr, or Ba as the hydrogen resisting agent to a glass raw material such as; for example, SiCl4 is integrally provided to the outside of the core 1 consisting of the quartz glass, etc., and further, soot of fine particles made of synthetic quartz glass is deposited by an external deposition method, etc., to the outside thereof to form a jacket 2, by which a preform is obtd. The transparent base material vitrified by heating such preform to about 1,500 deg.C is then heated and drawn. |
