Optical dispersion compensation in the electrical domain in an optical communications system
First Claim
1. A method of compensating dispersion of a communications signal conveyed through an optical communications system, the method comprising steps of:
- deriving a compensation function that substantially mitigates the dispersion imparted to the communications signal by the optical communications system;
digitally processing an electrical input signal using the compensation function to generate a predistorted electrical signal comprising a pair of orthogonal signal components; and
independently modulating a phase of an optical signal using a first one of the pair of orthogonal signal components of the predistorted electrical signal and an amplitude of the optical signal using a second one of the pair of orthogonal signal components of the predistorted electrical signal to generate a corresponding predistorted optical signal for tansmission through the optical communications system.
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Abstract
Optical dispersion imposed on a communications signal conveyed through an optical communications system is compensated by modulating the communications signal in the electrical domain. A compensation function is determined that substantially mitigates the chromatic dispersion. The communications signal is then modulated in the electrical domain using the compensation function. In preferred embodiments, compensation is implemented in the transmitter, using a look-up-table and digital-to-analog converter to generate an electrical predistorted signal. The electrical predistorted signal is then used to modulate an optical source to generate a corresponding predistorted optical signal for transmission through the optical communications system.
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Citations
44 Claims
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1. A method of compensating dispersion of a communications signal conveyed through an optical communications system, the method comprising steps of:
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deriving a compensation function that substantially mitigates the dispersion imparted to the communications signal by the optical communications system; digitally processing an electrical input signal using the compensation function to generate a predistorted electrical signal comprising a pair of orthogonal signal components; and independently modulating a phase of an optical signal using a first one of the pair of orthogonal signal components of the predistorted electrical signal and an amplitude of the optical signal using a second one of the pair of orthogonal signal components of the predistorted electrical signal to generate a corresponding predistorted optical signal for tansmission through the optical communications system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A dispersion compensation system for compensating optical dispersion of a communications signal conveyed through an optical communications system, the dispersion compensation system comprising:
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derivation means for deriving a compensation function that substantially mitigates the dispersion imparted to the communications signal by the optical communications system; a compensation processor for processing an electrical input signal using the compensation function to generate a predistorted electrical signal comprising two parallel orthogonal signal componenets; and modulating means for independently modulating a phase of an optical signal using a first obe of the pair of orthogonal signal components of the predistorted electrical signal and an amplitude of the optical signal using a second one of the pair of orthogonal signal components of the predistoeted electrical signal to generate a predistorted optical signal for transmission through the optical communications system. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A dispersion compensator for compensating optical dispersion of a communications signal conveyed through an optical communications system, the dispersion compensator being implemented in a transmitter of the optical communications system, and comprising:
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a digital filter for calculating successive digital sample values of the predistorted electrical signal comprising a pair of orthogonal signal components, based on the electrical input signal and the compensation function that substantially mitigates the dispersion imparted to the communication signal by the optical communication system ; and a respective digital-to-analog converter (DAC) for converting digital sample values of each orthogonal signal component into a into a corresponding analog signal component of the predistorted electrical signal for driving an optical modulation means so as to modulate a phase of an optical signal using a first one of the pair of analog signal components and modulate an amplitude of the optical signal using a second one of the pair of analog signal components to generate a corresponding predistorted optical signal for transmission through the optical communications system. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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Specification