Optical fiber and transmission system, and wavelength division multiplexing system
An optical fiber and fiber core technology, which can be used in cladding fibers, multi-layer core/cladding fibers, etc., and can solve problems such as unsatisfactory practicality.
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no. 1 approach
[0111] An optical fiber according to the first embodiment of the present invention was produced as a trial. No. 2 to No. 25 in Tables 1 to 3 show examples of optical fibers produced as prototypes, their structures, and optical characteristics. In No. 1 of Table 1, a standard SM optical fiber (ITU-T Recommendation G.652 standard) is similarly shown as a comparative example. In Tables 1 to 3, "Ge concentration" indicates the concentration of germanium doped in the inner core or outer core (converted to germanium oxide), and "F concentration" indicates the concentration of germanium doped in the inner core or outer core. Fluorine concentration. In addition, in the optical fibers of each of No. 2 to No. 25, the "relative Brillouin gain" was measured with the optical fiber of each example when the SBS light intensity measured with the optical fiber of the comparative example was set to 1. Relative value of SBS light intensity. Similarly, "relative threshold power" is a relative ...
no. 2 approach
[0122] The second embodiment relates to an SM optical fiber having an MFD of about 8.6 μm at a wavelength of 1310 nm. Such an optical fiber is commercialized as an optical fiber having reduced bending loss within a range satisfying ITU-T Recommendation G.652. 4A to 4C and Table 4 show the dopant (Ge, F) concentration distribution and relative refractive index difference when such an optical fiber is designed by a conventional method.
[0123] 【Table 4】
[0124] Radius [μm]
Ge concentration [mass%]
F concentration [mass%]
Relative refractive index difference [%]
center core
4.256
4.21
0.15
0.37
inner cladding
10.64
0.00
0.15
-0.05
outer cladding
62.5
0.00
0.00
0.00
[0125] With such a refractive index distribution, an optical fiber exhibiting the following optical characteristics can be obtained.
[0126] Fiber cut-off wavelength: 1.26μm.
[0127] MFD a...
no. 3 approach
[0142] The third embodiment relates to an optical fiber with further improved bending characteristics.
[0143] 8A to 8C show examples of low bending loss optical fibers based on conventional methods. This optical fiber has the concentration profile and refractive index profile shown in Table 6.
[0144] Radius [μm]
Ge concentration [mass%]
F concentration [mass%]
Relative refractive index difference [%]
center core
3.47
5.21
0.15
0.47
inner cladding
6.94
0.00
0.15
-0.05
groove
12.15
0.00
0.76
-0.25
outer cladding
62.50
0.00
0.00
0.00
[0145] With such a refractive index distribution, an optical fiber exhibiting the following optical characteristics can be obtained.
[0146] Fiber cut-off wavelength: 1.26μm.
[0147] MFD at a wavelength of 1310 nm: 7.36 μm.
[0148] MFD at a wavelength of 1550 nm: 8.19 μm.
[0149] Zero dispersi...
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