| 摘要 |
PROBLEM TO BE SOLVED: To provide a dispersion shift optical fiber capable of securing sufficient transmission capacity without causing any distortion in a transmission signal and performing wavelength division multiplex communication by using transmission light in the vicinity of a wavelength 1.55μm and an Er dope optical fiber type optical amplifier. SOLUTION: An outer peripheral side of a center core 3 is covered by a middle core 4, and its outer peripheral side is covered by an inside outer core 5, and its outer peripheral side is covered by an outside outer core 6, and a core 1 is formed, and its periphery is covered by a cladding 8, and the dispersion shift optical fiber is formed. When the refractive index of the central core 3 is defined n1 , the refractive index of the middle core 4 is n2 , the refractive index of the inside outer core 5 is n3 and the refractive index of the outside outer core 6 is n4 , the refractive index distribution structure of the core 1 satisfying n1 >n4 >n2 >n3 is formed. |
