Patent ID: 7085463

Claim:
An optical fiber, having a zero dispersion wavelength in a wavelength range of 1350 to 1410 nanometers; a dispersion of 2 to 8 ps/nm/km at a wavelength of 1550 nanometers; a dispersion slope of a positive value and not more than 0.05 ps/nm 2 /km at a wavelength of 1550 nanometers; a transmission loss of not more than 0.4 dB/km at a wavelength of 1380 nanometers; an increase of transmission loss of not more than 0.04 dB/km at a wavelength of 1380 nanometers after a hydrogen aging test; a transmission loss of not more than 0.25 dB/km at a wavelength of 1550 nanometers; and a bending loss of not more than 30 dB/m when the optical fiber is wound at a diameter of 20 millimeters at a wavelength of 1550 nanometers wherein a first core having a refractive index of n 1 , and located at the center of the optical fiber; a second core having a refractive index of n 2 , and surrounding the first core; a third core having a refractive index of n 3 , and surrounding the second core; and a cladding having a refractive index of n 4 , and surrounding the third core, where n 1 >n 3 >n 4 >n 2 and wherein the cladding includes an annular region having a refractive index of n 5 , where n 4 >n 5 .