# US 7,483,613 B2 · Chromatic dispersion compensating fiber

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- Number: US 7,483,613 B2
- Document ID: US7483613B2
- Status: Granted
- Kind: B2
- Application number: 11/934,451
- Filed: 2007-11-02
- Published: 2008-05-08
- Granted: 2009-01-27
- Earliest claimed: 2006-11-03
- Assignees: Draka Comteq B.V.
- Inventors: Marianne Bigot-Astruc; Louis-Anne De Montmorillon; Denis Molin; Pierre Sillard
- Web page: https://patentgrep.com/patent/US7483613B2

## CPC

- H04B 10/25253: {with dispersion management, i.e. using a combination of different kind of fibres in the transmission system}
- H04B: TRANSMISSION

## Abstract

Disclosed are an improved system and a related method for compensating the chromatic dispersion of a given length of a transmission fiber over a given spectral band by employing at least two chromatic dispersion compensating fibers that, with respect to the slope of the slope of the chromatic dispersion (SSi), have values of opposite signs.

## Claims

### Claim 1

An optical transmission system over a given spectral band, the system comprising:
a given length (L0) of an optical transmission fiber having, at a median wavelength (λ0) of the given spectral band, a given chromatic dispersion D0(λ0) and a given slope of the chromatic dispersion S0(λ0); and
at least two chromatic dispersion compensating fibers (DCFi) of respective length (Li), each dispersion compensating fiber having, at the median wavelength (λ0), given values of chromatic dispersion Di(λ0) and of slope of the chromatic dispersion Si(λ0) that substantially satisfy the following equations:
D
0
⁡
(
λ
0
)
·
L
0
+
∑
i
⁢
(
D
i
⁡
(
λ
0
)
·
Li
)
=
0
⁢
⁢
ps
⁢
/
⁢
nm
S
0
⁡
(
λ
0
)
·
L
0
+
∑
i
⁢
(
S
i
⁡
(
λ
0
)
·
Li
)
=
0
⁢
⁢
ps
⁢
/
⁢
nm
2
wherein at least two of the dispersion compensating fibers have values for the slope of the slope of the dispersion SSi(λ0) of opposite signs.

### Claim 2 (depends on 1)

An optical transmission system according to claim 1, wherein the values for the slope of the slope of the dispersion (SSi) of the compensation fibers (DCFi) also substantially satisfy the following equation:

∑
i
⁢
(
SS
i
⁡
(
λ
0
)
·
L
i
)
L
0

<
0.002
⁢
⁢
ps
⁢
/
⁢
nm
3
⁢
/
⁢
km
.

### Claim 3 (depends on 1)

An optical transmission system according to claim 1, wherein the given spectral band has a spectral width that is 40 nm or less.

### Claim 4 (depends on 1)

An optical transmission system according to claim 1, wherein the given spectral band is chosen from among all or part of the C or C+ band, the L band, or the S band.

### Claim 5 (depends on 1)

An optical transmission system according to claim 1, wherein, at the median wavelength (λ0) of the given spectral band, the optical transmission fiber has a DOS value of less than 150 nm.

### Claim 6

An optical transmission system over a spectral band having a spectral width of about 40 nm or less, the system comprising:
a given length (L0) of an optical transmission fiber having, at a median wavelength (λ0) of the given spectral band, a given chromatic dispersion D0(λ0) and a given slope of the chromatic dispersion S0(λ0); and
at least two chromatic dispersion compensating fibers (DCFi) of respective length (Li), the chromatic dispersion compensating fibers in communication with the optical transmission fiber;
wherein each dispersion compensating fiber has, at the median wavelength (λ0), given values of chromatic dispersion Di(λ0) and of slope of the chromatic dispersion Si(λ0) that substantially satisfy the following equations:
D
0
⁡
(
λ
0
)
·
L
0
+
∑
i
⁢
(
D
i
⁡
(
λ
0
)
·
Li
)
=
0
⁢
⁢
ps
⁢
/
⁢
nm
S
0
⁡
(
λ
0
)
·
L
0
+
∑
i
⁢
(
S
i
⁡
(
λ
0
)
·
Li
)
=
0
⁢
⁢
ps
⁢
/
⁢
nm
2
wherein at least two of the dispersion compensating fibers have values for the slope of the slope of the dispersion SSi(λ0) of opposite signs; and
wherein the values for the slope of the slope of the dispersion (SSi) of the compensation fibers (DCFi) also substantially satisfy the following equation:

∑
i
⁢
(
SS
i
⁡
(
λ
0
)
·
L
i
)
L
0

<
0.002
⁢
⁢
ps
⁢
/
⁢
nm
3
⁢
/
⁢
km
.

### Claim 7 (depends on 6)

An optical transmission system according to claim 6, wherein the given spectral band has a spectral width that is 35 nm or less.

### Claim 8 (depends on 6)

An optical transmission system according to claim 6, wherein, at the median wavelength (λ0) of the given spectral band, the optical transmission fiber has a DOS value of less than about 100 nm.

### Claim 9

A method for compensating the chromatic dispersion of a given length (L0) of a transmission fiber over a given spectral band, the method comprising:
selecting at least two chromatic dispersion compensating fibers (DCFi) each having a given value for the slope of the slope of the dispersion (SSi) at a median wavelength (λ0) of the given spectral band, at least two dispersion compensating fibers being chosen with values for the slope of the slope of the dispersion SSi(λ0) of opposite signs; and
assembling given lengths (Li) of each dispersion compensating fiber;
wherein the dispersion compensating fibers are selected and the lengths of each selected fiber are chosen to substantially satisfy the following equation:

∑
i
⁢
(
SS
i
⁡
(
λ
0
)
·
L
i
)
L
0

<
0.002
⁢
⁢
ps
⁢
/
⁢
nm
3
⁢
/
⁢
km
.

### Claim 10 (depends on 9)

The method for compensating the chromatic dispersion of claim 9, wherein the dispersion compensating fibers (DCFi) are selected to substantially satisfy the following equations:
D
0
⁡
(
λ
0
)
·
L
0
+
∑
i
⁢
(
D
i
⁡
(
λ
0
)
·
Li
)
=
0
⁢
⁢
ps
⁢
/
⁢
nm
S
0
⁡
(
λ
0
)
·
L
0
+
∑
i
⁢
(
S
i
⁡
(
λ
0
)
·
Li
)
=
0
⁢
⁢
ps
⁢
/
⁢
nm
2
and wherein Di(λ0) and Si(λ0), respectively, are the values of dispersion and dispersion slope of the dispersion compensating fibers at the median wavelength (λ0) of the given spectral band, and the transmission fiber of the length (L0) has, at the median wavelength (λ0) of the given spectral band, a given chromatic dispersion D0(λ0) and a given slope of the chromatic dispersion S0(λ0).