Optical fiber having low non-linearity for WDM transmission
View Patent ↗An optical transmission fiber has a refractive index profile with an area of increased index of refraction at the inner core of the fiber, an annular region positioned radially outward from the inner core with an index of refraction exceeding the index of the inner core, and at least a low dopant content region in a cross-sectional region between the inner core and the annular region. A low loss cladding layer surrounds the core region. The optical transmission fiber with this segmented core profile provides a high effective area, low non-linearity coefficient, nonzero dispersion, and relatively flat dispersion slope.
1. An optical transmission fiber with a low non-linearity coefficient γ and high effective area for use in a WDM optical transmission system, the optical transmission fiber comprising:
a core region comprising:
a glass inner core having a first maximum refractive index difference Δn 1 ;
a first glass layer radially surrounding the inner core, having a refractive index difference Δn 2 less than Δn 1 ; and
a second glass layer radially surrounding the first layer, having a second maximum refractive index difference Δn 3 greater than zero; and
a low loss cladding surrounding the second glass layer,
wherein the non-linearity coefficient γ is less than about 2 W −1 km −1 , the effective area is greater than 45 μm 2 , a total dispersion for the fiber in a wavelength range of 1530 nm to 1565 nm is about 5 to 10 ps/nm/km, and a dispersion slope for the fiber at a wavelength of 1550 nm is less than or equal to about 0.06 ps/nm 2 /km.
2. The optical transmission fiber according to claim 1 , wherein a fiber cutoff wavelength is less than 1480 nm.
3. The optical transmission fiber according to claim 1 , wherein a macrobending attenuation coefficient for the fiber at a wavelength of 1550 nm is less than 1 dB/km.
4. The optical transmission fiber according to claim 1 , wherein said first glass layer contains refractive index modifying dopants.
5. The optical transmission fiber according to claim 1 , wherein a dopant content of said first glass layer is low.
6. The optical transmission fiber according to claim 1 , wherein said second maximum refractive index difference Δn 3 is greater than refractive index difference Δn 2 .
7. An optical fiber according to claim 1 , wherein said first maximum refractive index different Δn 1 is greater than or equal to 0.0082 and less than or equal to 0.0095.
8. The optical fiber according to claim 1 , wherein the glass inner core has a core radius r 1 comprised between about 3.6 μm and about 4.2 μm.