US2012027343A1PendingUtilityA1
Wavelength division multiplex optical regeneration system and wavelength division multiplex optical regeneration method
Est. expiryJun 11, 2022(expired)· nominal 20-yr term from priority
Inventors:Koji IgarashiShunichi MatsushitaShu NamikiShigehiro TakasakaTakashi InoueHideaki TobiokaJiro Hiroishi
H04B 10/299H04B 10/25077G02F 1/3513
42
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Claims
Abstract
An optical regeneration system for regenerating a degenerated signal light, comprising a regeneration device having at least one of a soliton converter, a pulse roller, a Kerr-shutter and a soliton purifier. The solilton converter uses an anomalaous-dispersion fiber (ADF) having a fiber length up to three times the soliton frequency, and the pulse roller is provided with a pulse roller fiber having high non-linear characteristics. The Kerr-shutter comprises an optical LO (local oscillation) generator for generating an optical LO on an OPLL (optical phase locked loop), a phase comparator for detecting the phase difference between an externally-input signal light and an optical LO, and a control unit for regulating the repeated frequency of an optical LO based on the phase difference. The soliton purifier has a soliton fiber disposed between two optical fibers.
Claims
exact text as granted — not AI-modified1 . A Kerr-shutter comprising a demultiplexer, an OPLL (Optical Phase Locked Loop), and an optical switch.
2 . The Kerr-shutter according to claim 1 , wherein L Loop is determined by satisfying the following equation:
Δω( L Loop )< v·X/n·L A-B
where Δω: bit rate difference in the OPLL, L Loop : loop length, v: velocity of the light in the optical fiber, L A-B : length of fiber between the demultiplexer and the optical switch, n: refraction index of the fiber, and X: arbitrary number.
3 . The Kerr-shutter according to claim 1 , wherein said OPLL comprises an optical LO generator generating an optical LO, a phase comparator detecting phase difference between an external optical signal and said optical LO signal, and a controller to control a frequency of said LO signal based on the phase difference.
4 . The Kerr-shutter according to claim 3 , wherein said phase comparator includes an FWM unit generating an FWM light, an optical filter and a photo receiving device.
5 . The Kerr-shutter according to claim 3 , wherein said FWM unit adopts either a high nonlinear optical fiber, a PPLN (Periodically-poled LiNO 3 ), or an SOA (Semi-conductive Optical Amplifier).
6 . The Kerr-shutter according to claim 4 , wherein said photo receiving device has a pulse roller which is placed in a front stage and monitors frequency characteristic of pulses entering to the photo receiving device.
7 . The Kerr-shutter according to claim 3 , wherein said LO generator has a beat light generator.
8 . The Kerr-shutter according to claim 7 , wherein said beat light generator comprises at least one semiconductor laser which emits a CW light with at least two frequency components and an optical coupler which mixes said CW lights.
9 . The Kerr-shutter according to claim 8 , wherein said semiconductor lasers are driven in series.
10 . The Kerr-shutter according to claim 1 , wherein an optical fiber compressor is inserted between said beat light generator and said optical switch.
11 . The Kerr-shutter according to claim 3 , wherein said phase comparator includes a PD (Photo Diode), a Loop Filter and an LD controller, and wherein said PD generates a photo current by a two photon absorption effect.
12 . The Kerr-shutter according to claim 11 , wherein said PD is made of a silicon avalanche photodiode (SiAPD).
13 . The Kerr-shutter according to claim 1 , wherein said optical switch includes an FWM unit, an optical filter and a phase controller.
14 . The Kerr-shutter according to claim 13 , wherein said phase controller is controlled so that the phase control output does not to drift for change of an ambient temperature.
15 . The Kerr-shutter according to claim 14 , wherein said phase control output is controlled by a feedback of an output pulse.
16 . The Kerr-shutter according to claim 13 , wherein said FWM unit has a relation expressed by the following equation:
Δ
v
>
Δ
v
p
+
Δ
v
s
2
where;
Δν: frequency delta (detuning amount) between a pump light and an optical signal,
Δν p : spectrum width of an input pumping pulse, and
Δν s : spectrum width of an input signal pulse.
17 . The Kerr-shutter according to claim 13 , wherein said FWM unit has a relation expressed by the following equation:
Δ L>Δν p +(Δν s /2)
where; ΔL: fiber length, Δν p : spectrum width of an input pumping pulse, and Δν s : spectrum width of an input signal pulse.
18 . The Kerr-shutter according to claim 13 , wherein said fiber length L is determined by the following equation:
1
<
L
L
NL
=
γ
P
0
L
γ
P
P
L
≤
3
π
2
19 . The Kerr-shutter according to claim 13 , wherein the fiber length L of said FMW unit is determined by the following equation:
L
L
SOD
<
1
2
,
L
L
TOD
<
1
2
β
3
<
1.7628
3
2
Δ
t
p
3
L
β
3
<
1.7628
2
4
π
Δ
t
s
2
L
Δ
v
20 . The Kerr-shutter according to claim 13 , which is designed by the following steps of:
a process to determine a detuning amount Δν which is a value to avoid a spectrum overlapping using the equation regarding the pumping pulse (Δt p , Δν p ) and the signal pulse (Δt s , Δν s );
Δ
v
>
Δ
v
p
+
Δ
v
s
2
a process to determine the fiber length L to obtain the FWM bandwidth exceeding 2Δν;
a process to determine the pumping peak power P p which can generate an FWM without distortion in the spectrum waveform using the equation;
1
<
L
L
NL
=
γ
P
0
L
γ
P
P
L
≤
3
π
2
and
a process to determine the third order dispersion value β 3 which is necessary to suppress a time waveform distortion of the pulse during the fiber transmission using the following equation:
β
3
<
1.7628
3
2
Δ
t
p
3
L
β
3
<
1.7628
2
4
π
Δ
t
s
2
L
Δ
v
21 . The Kerr-shutter which further comprises an optical LO generator, and a controller, wherein the FWM unit is commonly shared with said optical phase comparator in claim 4 and an optical switch including an FWM unit, an optical filter and a phase controller.Join the waitlist — get patent alerts
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