Method for regulating OSNR in a fiber optic communication line using Raman amplification
AssigneeECI Telecom Ltd.
InventorEyal Lichtman
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Abstract
A method for selecting a relation between a gain Gf of a Forward Raman Amplifier (FRA) at a transmitting end of a fiber optic transmission line and an optical signal to noise ratio (OSNR) at a receiving end of the fiber optic transmission line satisfying limitations for real long transmission lines. The method comprises selecting the relation using a regulation function ROSNR obtained either in the form of a simplified equation, or in the form of one or more linear approximations of the function for practical ranges of the FRA gain.
Claims11
A method for selecting a relation between a gain Gf of a Forward Raman Amplifier (FRA) at a transmitting end of a fiber optic transmission line and an optical signal to noise ratio (OSNR) at a receiving end of the fiber optic transmission line, provided that said transmission line operates under a non-linearity limit, and power loss L of the fiber optic transmission line is much greater than a selected value of the gain Gf;
- the method comprises selecting said relation by using a regulation function ROSNR of OSNR improvement, defined substantially close to the following expression:
- ROSNR=Gf/RNL (1)
- where RNL is a factor of the FRA, calculated substantially close to the following:
- RNL=μGf(ln(Gf))−μ[Γ(μ)−Γ(μ,ln(Gf))] (2)
- where μ=α/β,
- α is the fiber attenuation at the signal wavelength,
- β is the fiber attenuation of the Raman pump wavelengths,
- Γ(x) and Γ(x, y) are the Gamma and the incomplete Gamma functions, respectively.
A method for selecting a relation between a gain Gf of a Forward Raman Amplifier (FRA) at a transmitting end of a fiber optic transmission line and an optical signal to noise ratio (OSNR) at a receiving end of the fiber optic transmission line, provided that said transmission line operates under a non-linearity limit, and power loss L of the fiber optic transmission line is much greater than a selected value of the gain Gf;
- the method comprises selecting said relation using a regulation function ROSNR in the form of one or more of the following approximated linear sections covering a practical range of the FRA gain 0 to 20 dB:
- ROSNR=0.39Gf for 0 dB<Gf≦6 dB (3)
- ROSNR=0.27Gf+0.7 for 6 dB<Gf≦13 dB (4)
- ROSNR=0.2Gf+1.55 for 13 dB<Gf≦20 dB (5).
A method for selecting a relation between a gain Gf of a Forward Raman Amplifier (FRA) at a transmitting end of a fiber optic transmission line and an optical signal to noise ratio (OSNR) at a receiving end of the fiber optic transmission line, provided that said transmission line operates under a non-linearity limit, and power loss L of the fiber optic transmission line is much greater than a selected value of the gain Gf;
- the method comprises selecting said relation using a regulation function ROSNR in the form of an approximated linear section covering a practical range of the FRA gain 0 to 12 dB:
- ROSNR=0.35Gf 0 dB<Gf≦12 dB (6).
Dependencies are inferred from the claim text.