Optical transmission system with dispersion compensating optical fiber

An optical transmission system comprising:

• (a) a light source;
• (b) a single-mode optical fiber connected to the light source and having zero dispersion at a predetermined wavelength between 1290 nm and 1330 nm;
• (c) an erbium-doped fiber connected to said single-mode optical fiber;
• (d) A bobbin having a diameter of between 40 mm and 80 mm both inclusive;
• (e) a dispersion compensating fiber connected to said erbium-doped fiber and wound around said bobbin, wherein a bending loss thereof when wound around said bobbin is smaller than 0.01 dB/m at the wavelength 1.55 .mu.m, wherein said dispersion compensating fiber has a core, a first cladding surrounding the core, and a second cladding surrounding the first cladding, and wherein the dispersion compensating fiber satisfies the following relations:
• n1<n2<nc,
• 3 .mu.m<2Da<4 .mu.m,
• 0.4<(Da/Db)<0.6,
• 0.02<(nc-n2)/n2<0.03,
• 0.004<(n2-n1)/n2<0.01,
• where
• nc is a refractive index of the core;
• n1 is a refractive index of the first cladding;
• n2 is a refractive index of the second cladding;
• 2Da is a diameter of the core;
• and
• 2Db is an outer diameter of the first cladding.

A dispersion compensating optical fiber, comprising:

• (a) a core;
• (b) a first cladding surrounding the core;
• and
• (c) a second cladding surrounding the first cladding;
• and wherein said dispersion compensating fiber satisfies the following relations:
• n1<n2<nc,
• 3 .mu.m<2Da<4 .mu.m,
• 0.4<(Da/Db)<0.6,
• 0.02<(nc-n2)/n2<0.03,
• 0.004<(n2-n1)/n2<0.01,
• where
• nc is a refractive index of the core;
• n1 is a refractive index of the first cladding;
• n2 is a refractive index of the second cladding;
• 2Da is a diameter of the core;
• and
• 2Db is a outer diameter of the first cladding.