OPTICAL FIBER FOR AMPLIFICATION

摘要

This invention provides EDF which enables amplification properties to be easily predicted and is high in production stability. The EDF comprises a core and a clad each composed mainly of quartz glass. The core contains an erbium element as an additive element. The addition concentration of erbium is not less than 500 wtppm and not more than 2500 wtppm. The cutoff wavelength is not less than 850 nm and not more than 1450 nm. The mode field diameter is not less than 4.5 µm and not more than 6.5 µm. The polarized wave mode dispersion is not more than 0.1 [ps/10 m]. The number of coordination of O element around the erbium element in the core is not less than 1 and not more than 8. The bond distance between the erbium element and the O element in the core is not less than 0.225 nm and not more than 0.235 nm.