Graded-index multimode fiber and manufacturing method therefor
AssigneeFujikura Ltd.
InventorsNing Guan, Katsuhiro Takenaga, Kuniharu Himeno
Life of this patent
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Abstract
A graded-index multimode fiber includes a core made of silica glass, the core having a central region and an outer peripheral region, and a cladding which is provided at an outer periphery of the core. The central region contains one of germanium and phosphorus, and the outer peripheral region contains fluorine.
Claims10
A graded-index multimode fiber comprising:
- a silica glass core comprising a central region and an outer peripheral region;
- and
- a cladding provided at an outer periphery of the core,
- wherein the central region of the core contains one of germanium and phosphorus, and the outer peripheral region of the core contains fluorine, and
- the graded-index multimode fiber has a refractive index profile which satisfies the following:
- n
-
- (
- r
- )
- =
- {
- n
- 1
-
- [
- 1
- -
- F
-
- (
- r
- )
- ]
- 1
- /
- 2
-
- (
- 0
- ≤
- r
- ≤
- a
- )
- n
- 1
-
- [
- 1
- -
- F
-
- (
- a
- )
- ]
- 1
- /
- 2
-
- (
- r
- >
- a
- )
-
-
- F
-
- (
- r
- )
- =
- {
- 2
-
- Δ
- 1
-
- (
- r
- a
- 0
- )
- α
- 1
-
- r
- <
- a
- 0
- 2
-
- Δ
- 2
-
- (
- r
- a
- )
- α
- 2
-
- a
- 0
- ≤
- r
- ≤
- a
-
-
- n
- 1
- 2
-
- [
- 1
- -
- 2
-
- Δ
- 2
-
- (
- a
- 0
- a
- )
- α
- 2
- ]
- =
- n
- 0
- 2
-
-
- n
- 1
- 2
-
- [
- 1
- -
- 2
-
- Δ
- 1
- ]
- =
- n
- 0
- 2
- wherein n(r) is a refractive index of the fiber at a distance “r” from the center of the core, n1 is a refractive index at the center of the core, Δ1 is a maximum relative refractive index difference of one of germanium and phosphorus contained in the central region of the core with respect to the cladding, Δ2 is a maximum relative refractive index difference of fluorine contained in the central region of the core with respect to the cladding, “a” is a core radius, and α1 is a refractive index profile exponential parameter of the one of germanium and phosphorus contained in the central region of the core, α2 is a refractive index profile exponential parameter of fluorine contained in the outer peripheral region of the core, a0 is a distance between the central and outer peripheral regions of the core, and n0 is a refractive index of pure silica.
A method for manufacturing a graded-index multimode fiber, the graded-index multimode fiber comprising a core and a cladding and being essentially made of silica glass, the graded-index multimode fiber being doped with germanium and fluorine, the graded-index multimode fiber having a refractive index n(r) at a distance “r” from the center of the core, comprising forming the graded-index multimode fiber, wherein germanium and fluorine are doped so that a variation in a refractive index profile exponential parameter αi(i =1, 2) with a change in wavelength becomes zero;
- and
- n
-
- (
- r
- )
- =
- {
- n
- 1
-
- [
- 1
- -
- F
-
- (
- r
- )
- ]
- 1
- /
- 2
-
- (
- 0
- ≤
- r
- ≤
- a
- )
- n
- 1
-
- [
- 1
- -
- F
-
- (
- a
- )
- ]
- 1
- /
- 2
-
- (
- r
- >
- a
- )
-
-
- F
-
- (
- r
- )
- =
- ∑
- i
- =
- 1
- 2
-
- 2
-
- Δ
- i
-
- (
- r
- a
- )
- α
- i
-
-
- α
- i
- =
- 2
- -
- 2
-
- n
- 1
- N
- 1
-
- λ
- Δ
- i
-
- ⅆ
- Δ
- i
- ⅆ
- λ
- -
- 12
- 5
-
- Δ
- wherein F is a fiber shape function, Δ=Δ1+Δ2, is a refractive index at the center of the core, N1 is a group index at the center of the core, “a” is a core radius, λ is a wavelength, Δi is a relative refractive index difference at the center of the core with respect to the cladding for each of the refractive index profiles, and i=1 or 2 representing gennanium or fluorine.
A method of manufacturing a graded-index multimode fiber suitable for transmission of wavelength division multiplexed data, comprising:
- forming a core comprising silica glass, the core comprising a central region and an outer peripheral region;
- and
- forming a cladding at an outer periphery of the core;
- wherein the central region of the core contains at least one of germanium and phosphorus, and the outer peripheral region of the core contains fluorine, and
- n
-
- (
- r
- )
- =
- {
- n
- 1
-
- [
- 1
- -
- F
-
- (
- r
- )
- ]
- 1
- /
- 2
-
- (
- 0
- ≤
- r
- ≤
- a
- )
- n
- 1
-
- [
- 1
- -
- F
-
- (
- a
- )
- ]
- 1
- /
- 2
-
- (
- r
- >
- a
- )
-
-
- F
-
- (
- r
- )
- =
- ∑
- i
- =
- 1
- 2
-
- 2
-
- Δ
- i
-
- (
- r
- a
- )
- α
- i
-
-
- α
- i
- =
- 2
- -
- 2
-
- n
- 1
- N
- 1
-
- λ
- Δ
- i
-
- ⅆ
- Δ
- i
- ⅆ
- λ
- -
- 12
- 5
-
- Δ
- wherein F is a fiber shape function, Δ=Δ1+Δ2, n1 is a refractive index at the center of the core, N1 is a group index at the center of the core, “a” is a core radius, λ is a wavelength, Δi is a relative refractive index difference at the center of the core with respect to the cladding for each of the refractive index profiles, and i =1 or 2 representing germanium or fluorine.
A method of manufacturing a graded-index multimode fiber suitable for transmission of wavelength division multiplexed data, comprising:
- forming a core comprising silica glass, the core comprising a central region and an outer peripheral region;
- and
- forming a cladding at an outer periphery of the core;
- wherein the central region of the core contains at least one of germanium and phosphorus, and the outer peripheral region of the core contains fluorine, and
- the manufactured graded-index multimode fiber has a refractive index profile which satisfies the following:
- n
-
- (
- r
- )
- =
- {
- n
- 1
-
- [
- 1
- -
- F
-
- (
- r
- )
- ]
- 1
- /
- 2
-
- (
- 0
- ≤
- r
- ≤
- a
- )
- n
- 1
-
- [
- 1
- -
- F
-
- (
- a
- )
- ]
- 1
- /
- 2
-
- (
- r
- >
- a
- )
-
-
- F
-
- (
- r
- )
- =
- {
- 2
-
- Δ
- 1
-
- (
- r
- a
- 0
- )
- α
- 1
-
- r
- <
- a
- 0
- 2
-
- Δ
- 2
-
- (
- r
- a
- )
- α
- 2
-
- a
- 0
- ≤
- r
- ≤
- a
-
-
- n
- 1
- 2
-
- [
- 1
- -
- 2
-
- Δ
- 2
-
- (
- a
- 0
- a
- )
- α
- 2
- ]
- =
- n
- 0
- 2
-
-
- n
- 1
- 2
-
- [
- 1
- -
- 2
-
- Δ
- 1
- ]
- =
- n
- 0
- 2
- wherein n(r) is a refractive index of the fiber at a distance “r” from the center of the core, n1 is a refractive index at the center of the core, Δ1 is a maximum relative refractive index difference of one of germanium and phosphorus contained in the central region of the core with respect to the cladding, Δ2 is a maximum relative refractive index difference of fluorine contained in the central region of the core with respect to the cladding, “a” is a core radius, and α1 is a refractive index profile exponential parameter of the one of germanium and phosphorus contained in the central region of the core, α2 is a refractive index profile exponential parameter of fluorine contained in the outer peripheral region of the core, a0 is a distance between the central and outer peripheral regions of the core, and n0 is a refractive index of pure silica.
Dependencies are inferred from the claim text.