Optical communication system having an antiresonant dispersion map suppressing four wave mixing and cross phase modulation
View Patent ↗An optical communication system transmitting a plurality of channel wavelengths is provided. The system includes a transmitter unit, a receiver unit, and an optical transmission path interconnecting the transmitter and receiver units. The transmission path has a concatonation of optical fibers defining a dispersion map such that each of the channel wavelengths are located at FMX and XPM antiresonances at which FWM and XPM are suppressed.
1. An optical communication system transmitting a plurality of channel wave lengths, said system comprising:
a transmitter unit;
a receiver unit;
an optical transmission path interconnecting the transmitter and receiver units, said transmission path having a concatenation of optical fibers defining a dispersion map having a period and amplifier spacing selected such that both η XPM and η FWM are simultaneously minimized at a selected channel separation, wherein η XPM and η FWM are cross phase modulation efficiency and four wave mixing efficiency respectively, wherein cross phase modulation efficiency is computed from
η
XPM
=
a
2
Ω
m
2
(
D
Δ
λ
)
2
+
a
2
[
1
+
4
sin
2
(
Ω
D
Δ
λ
L
/
2
)
ⅇ
-
aL
(
1
-
ⅇ
-
aL
)
2
]
and wherein four wave mixing efficiency is computed by
η
=
a
2
N
2
(
a
2
+
Δ
β
2
)
[
1
+
4
ⅇ
-
a
1
amp
sin
2
(
Δ
β
l
amp
/
2
)
[
1
-
ⅇ
-
al
amp
]
2
]
sin
2
(
N
Δ
β
l
amp
/
2
)
sin
2
(
Δ
β
l
amp
/
2
)
.
2. The optical communication system of claim 1 further comprising a plurality of optical amplifiers periodically located along said optical transmission path.
3. The optical communication system of claim 2 wherein said dispersion map has a period substantially equal to the periodicity of the optical amplifiers.
4. The optical communication system of claim 3 wherein each period of the dispersion map comprises at least a plurality of constituent fiber having different dispersion values.
5. The optical communication system of claim 3 wherein each period of the dispersion map has a path average dispersion about equal to zero.
6. The optical communication system of claim 2 wherein said dispersion map has a period less than the periodicity of the optical amplifiers.
7. The optical communication system of claim 6 wherein each period of the dispersion map comprises at least a plurality of constituent optical fibers with different cross-sectional areas.
8. The optical communication system of claim 2 wherein each period of the dispersion map comprises at least a plurality of constituent optical fibers with different cross-sectional areas.
9. The optical communication system of claim 1 wherein each period of the dispersion map comprises at least a plurality of constituent fiber having different dispersion values.
10. The optical communication system of claim 1 wherein each period of the dispersion map comprises at least a plurality of constituent optical fibers with different cross-sectional areas.
11. The optical communication system of claim 1 wherein each period of the dispersion map has a path average dispersion about equal to zero.
12. A method of establishing a dispersion map for an optical transmission system transmitting a plurality of channel wavelengths, said optical transmission system having an optical transmission path that includes a plurality of optical amplifiers interconnected by respective transmission spans, said method comprising the steps of:
selecting a period for the dispersions map; and
based on the selected dispersion map period and a channel spacing between adjacent ones of the channel wavelengths, selecting a plurality of different dispersion values for each period of the dispersion map, the dispersion map having a period and amplifier spacing selected such that both η XPM and η FWM are simultaneously minimized at a selected channel separation, wherein η XPM and η FWM are cross phase modulation efficiency and four wave mixing efficiency respectively, wherein cross phase modulation efficiency is computed from
η
XPM
=
a
2
Ω
m
2
(
D
Δ
λ
)
2
+
a
2
[
1
+
4
sin
2
(
Ω
D
Δ
λ
L
/
2
)
ⅇ
-
aL
(
1
-
ⅇ
-
aL
)
2
]
and wherein four wave mixing efficiency is computed by
η
=
a
2
N
2
(
a
2
+
Δ
β
2
)
[
1
+
4
ⅇ
-
a
1
amp
sin
2
(
Δ
β
l
amp
/
2
)
[
1
-
ⅇ
-
al
amp
]
2
]
sin
2
(
N
Δ
β
l
amp
/
2
)
sin
2
(
Δ
β
l
amp
/
2
)
.
13. The method of claim 12 wherein said dispersion map has a period substantially equal to the periodicity of the optical amplifiers.
14. The method of claim 13 wherein each period of the dispersion map comprises at least a plurality of constituent fiber having different dispersion values.
15. The method of claim 12 wherein each period of the dispersion map comprises at least a plurality of constituent fiber having different dispersion values.
16. The method of claim 12 wherein said dispersion map has a period less than the periodicity of the optical amplifiers.
17. The method of claim 16 wherein each period of the dispersion map comprises at least a plurality of constituent optical fibers with different cross-sectional areas.
18. The method of claim 12 wherein each period of the dispersion map comprises at least a plurality of constituent optical fibers with different cross-sectional areas.
19. The method of claim 12 wherein each period of the dispersion map has a path average dispersion about equal to zero.