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AssigneeMPB Technologies Inc.
InventorsSerguei Papernyi, Vladimir Karpov, Wallace Clements
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A pumping scheme for distributed Raman amplification (DRA) in optical fiber telecommunication systems is disclosed in which pump energy at the wavelength(s) required for DRA of the transmitted optical signal(s) is developed within the transmission fiber through a series, n, where n≧1, of Raman conversions. In preferred embodiments, a ‘primary’ pump source of wavelength shorter than the ultimately desired pump wavelength(s) is launched into the fiber along with one or more significantly lower-power secondary ‘seed’ sources. The wavelength and power of the secondary source(s) are chosen such that, when combined with the high-power primary source, Raman conversions within the fiber ultimately lead to the development of high power at the desired pump wavelength(s). In another embodiment, one or more seed sources are replaced by reflecting means to return, into the fiber, backward-travelling amplified spontaneous Raman scattered light resulting from high power in the fiber at a wavelength one Raman shift below the desired seed wavelength. In either case, the high power at the wavelength(s) required for DRA of the signal(s) is developed over a distributed length of the fiber rather than being launched from a terminal point, as in the prior art. Consequently, the maximum power at the desired pump wavelength(s), and the peak signal gain, occur some distance into the fiber from the launch terminal. In one exemplary embodiment, a distributed Raman preamplifier, improved noise performance results, since the Raman gain occurs, on average, at a greater distance from the receiving terminal than with the standard pumping scheme.
A system for pumping a transmission fiber of an optical fiber telecommunications span to produce distributed Raman gain in the fiber for amplifying signals being transmitted along the fiber span, comprising:
A system for applying dynamic control of the magnitude and/or spectral profile of the distributed Raman gain at, or near, a signal launch terminal of an optical fiber telecommunications span in which counter-propagating distributed Raman preamplification is being applied at a receiving or repeater end of the span or at some intermediate point along the span, resulting in residual energy at final direct-pumping wavelengths λf1 . . . λfk nearing said signal launch terminal, said system comprising:
A method of pumping a transmission fiber of an optical fiber telecommunications span to produce distributed Raman gain in the fiber for signals being transmitted along said fiber span, said method comprising the steps of:
A method of applying dynamic control of the magnitude and/or the spectral profile of the distributed Raman gain at, or near, a signal launch terminal of an optical fiber telecommunications span in which counter-propagating distributed Raman preamplification is being applied at a receiving or repeater end of the span or at some intermediate point along the span, resulting in residual energy at final direct-pumping wavelengths λf1 . . . λfk nearing said signal launch terminal, said method comprising the steps of:
A method of pumping a transmission fiber of an optical fiber telecommunications span to produce distributed Raman gain in the fiber for signals being transmitted along said fiber span, said method comprising the steps of:
The system of claim 4, wherein said optical source providing energy at a particular one of said secondary seed wavelengths λs1 . . . λsn comprises a laser diode or a pair of polarization-multiplexed laser diodes of equal wavelength.
The system of claim 4, wherein said optical source providing energy at a particular one of said one or more secondary seed wavelengths λs1 . . . λsn is a wavelength-tunable source.
Dependencies are inferred from the claim text.