Raman amplifying device and method for pump modulation
AssigneeAlcatel
InventorsCatherine Martinelli, Dominique Mongardien
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Abstract
The invention is dealing with a Raman amplifying device comprising an optical path, pump sources for generating a plurality of Raman pump signals and means for coupling the plurality of Raman pump signals into the optical path for backward pumping. The plurality of optical Raman pump signals are time-division multiplexed by multiplexing controlling means and the controlling means apply a modulation frequency beyond the corner frequency of the co-propagating modulation transfer function. The method to modulate the time division multiplexed Raman signal gives a condition to avoid the increase of double Rayleigh scattering noise.
Claims8
A Raman amplifying device for amplifying signals (S1, S2 . . . S n) with wavelengths λS1, λS2 . . . λSn comprising an optical path, pump sources (P1,P2 . . . PN) for generating a plurality of Raman pump signals (λ1,λ2,. . . λN) for backward pumping and means for coupling (21, 22, . . . 2N)) the plurality of Raman pump signals into the optical path, wherein the plurality of optical Raman pump signals are time-division multiplexed by multiplexing controlling means (41, 42, . . . 4N) for time-division multiplexing the plurality of optical Raman pump signals such that the time-division multiplexing frequency is higher than the minimal corner frequency fc of the co-propagating pump-to-signal modulation transfer function among the co-propagating pump-to-signal modulation transfer functions that implicate the signals (S1, S2 . . . Sn) and the pumps (P1,P2 . . . PN):
- f
- C
- =
- MIN
- i
- ,
- j
-
- {
- α
- Pi
- 2
-
- π
-
-
-
- 1
- V
- Sj
- -
- 1
- V
- Pi
-
- }
- where VSj and VPi are the group velocities of the signal Sj and the Raman pump signal Pi, αPi is the attenuation of the fiber at the pump wavelength λPi.
Method for time multiplexing a plurality of Raman pump signals in a amplifying device for amplifying signals (S1, S2 . . . Sn) with wavelengths λS1, λS2 . . . λSn comprising an optical path, pump sources (P1,P2. . . PN) for generating a plurality of Raman pump signals (λ1,λ2, . . . λN) for backward pumping and means for coupling (21,22, . . . 2 N)) the plurality of Raman pump signals into the optical path, wherein the plurality of optical Raman pump signals are time-division multiplexed by multiplexing controlling means (41,42, . . . 4N) characterized by the step:
- multiplexing the pumps in time so that the time-division multiplexing frequency is higher than the minimal corner frequency fc of the co-propagating pump-to-signal modulation transfer function among the co-propagating pump-to-signal modulation transfer functions that implicate the signals (S1,S2 . . . Sn) and the pumps (P1,P2 . . . PN):
- f
- C
- =
- MIN
- i
- ,
- j
-
- {
- α
- Pi
- 2
-
- π
-
-
- 1
- V
- Sj
- -
- 1
- V
- Pi
-
- }
- where VSj and VPi are the group velocities of the signal Sj and the Raman pump signal Pi, αPi is the attenuation of the fiber at the pump wavelength αPi.
Dependencies are inferred from the claim text.