Dispersion-shifted fiber

A dispersion-shifted fiber mainly comprising silica glass and having a substantially zero-dispersion wavelength within the range of 1.4 .mu.m to 1.7 .mu.m, said dispersion-shifted fiber comprising:

• an inner core containing at least fluorine, said inner core having a first refractive index and a first outer diameter a;
• an outer core disposed around an outer periphery of said inner core and containing at least fluorine, said outer core having a second refractive index lower than said first refractive index and a second outer diameter b;
• an inner cladding disposed around an outer periphery of said outer core, said inner cladding having a third refractive index lower than said second refractive index;
• and
• an outer cladding disposed around an outer periphery of said inner cladding, said outer cladding having a fourth refractive index higher than said third refractive index, wherein said dispersion-shifted fiber satisfies the following conditions:
• 0.01%.ltoreq..DELTA.n.ltoreq.0.10%;
• and
• 30 .mu.m.ltoreq.c.ltoreq.60 .mu.m
• wherein .DELTA.n is relative refractive index difference of said outer cladding with respect to said inner cladding, and c is outer diameter of said inner cladding.