希土類元素添加光ファイバおよびそれを用いた広帯域光ファイハ増幅器

Japanese Patent JP3609924

B2

PROBLEM TO BE SOLVED: To provide optical fiber added with rare earth elements which has high gain, wide band and low noise index characteristics, and is low in power consumption and cost, and to provide a wide band optical fiber amplifier using it. SOLUTION: A circular sectional clad 15 having a refractive index nc is provided with a first core 11 having a diameter D and a high refractive index n01 (n01 >nc ) and consisting of quartz glass (SiO2 ) to which erbium(Er), phosphor (P) and aluminum(Al) are co-added substantially in the center, a first intermediate layer 1 having a thickness S2 and a low refractive index nm1 (nm1 =n01 ) and consisting of quartz glass (SiO2 ) to which erbium(Er), aluminum(Al) and germanium(Ge) are co-added to the circumference of the first intermediate layer 12, and a second intermediate layer 14 having a thickness S2 and a low refractive index nm2 (nm2