OPTICAL FIBER AND WAVEGUIDE

摘要

Disclosed is an optical fiber wherein bend loss is reduced while maintaining large MFD. Also disclosed is a waveguide using such an optical fiber. Specifically disclosed is an optical fiber (10) comprising a core portion (1) doped with impurities, a first cladding portion (2) which is arranged around the core portion (1) as a laminar fine structure having holes (3), and a second cladding portion (4) which is a laminar uniform medium arranged around the first cladding portion (2). The relative refractive index difference ( 1) between the core portion (1) and the second cladding portion (4) is not less than 0.4% but less than 1.0%. The ratio of the total cross sectional area of the holes (3) of the first cladding portion (2) relative to the total cross sectional area of the core portion (1), the first cladding portion (2) and the second cladding portion (4) is less than 20%. A waveguide is formed by using such an optical fiber (10).