Process for making a glass fiber with a core and two glass cladding layers and glass fiber made thereby

摘要

The glass fiber for an optical amplifier has a glass core, a first glass cladding, and a second glass cladding. The core has a composition, in mol %, of Bi2O3, 30-60; SiO2, 0.5-40; B2O3, 0.5-40; Al2O3, 0-30; Ga2O3, 0-20; Ge2O3, 0-25; La2O3, 0-15; Nb2O5, 0-10; SnO2, 0-30; alkali metal oxides, 0-40; and Er2O3, 0.05-8. The process for making the glass fiber includes first making a preform consisting of the core and the first glass cladding by drawing from a double crucible. Then the second glass cladding is formed around the preform by a rod-in-tube process. The glass claddings have a composition that includes a transition metal compound as an absorbent.