Method and system for a polarization mode dispersion tolerant optical homodyne detection system with optimized transmission modulation
DCFirst Claim
1. A method of compensating a quadrature modulated optical data signal for effects of chromatic dispersion occurring during transmission over optical fiber, the method comprising the steps of:
- separating in-phase and quadrature components of the optical data signal;
optoelectrically converting the in-phase and quadrature components of the optical data signal into in-phase and quadrature data signals;
applying a corrective function to the in-phase and quadrature data signals, the corrective function modifying the in-phase and quadrature data signals in a manner that precisely counteracts effects of chromatic dispersion on the in-phase and quadrature components of the optical data signal.
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Abstract
An optical homodyne communication system and method in which a side carrier is transmitted along with data bands in an optical data signal, and upon reception, the side carrier is boosted, shifted to the center of the data bands, and its polarization state is matched to the polarization state of the respective data bands to compensate for polarization mode dispersion during transmission. By shifting a boosted side carrier to the center of the data bands, and by simultaneously compensating for the effects of polarization mode dispersion, the provided system and method simulate the advantages of homodyne reception using a local oscillator. The deleterious effects of chromatic dispersion on the data signals within the data bands are also compensated for by applying a corrective function to the data signals which precisely counteracts the effects of chromatic dispersion.
31 Citations
16 Claims
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1. A method of compensating a quadrature modulated optical data signal for effects of chromatic dispersion occurring during transmission over optical fiber, the method comprising the steps of:
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separating in-phase and quadrature components of the optical data signal; optoelectrically converting the in-phase and quadrature components of the optical data signal into in-phase and quadrature data signals; applying a corrective function to the in-phase and quadrature data signals, the corrective function modifying the in-phase and quadrature data signals in a manner that precisely counteracts effects of chromatic dispersion on the in-phase and quadrature components of the optical data signal. - View Dependent Claims (2)
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3. A receiver for receiving and processing an optical data signal, the optical data signal including at least two data bands and at least one side carrier, each of the at least two data bands including a pair of quadrature modulated data signals, the receiver comprising:
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a side carrier boosting module, the side carrier boosting module for increasing an amplitude of the at least one side carrier relative to the at least two data bands; a side carrier shifting module coupled to the side carrier boosting module, the side carrier shifting module for shifting the at least one side carrier into at least two shifted carriers, each of the at least two shifted carriers shifted to a center of one of the at least two data bands; and means for compensating polarization mode dispersion coupled to the side carrier shifting module, the means for compensating adjusting a polarization state of one of; a) each of the at least two shifted carriers to match a polarization state of one of the at least two data bands; and b) the at least two data bands to match a polarization state of the at least two shifted carriers. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of correcting a quadrature modulated optical data signal for effects of chromatic dispersion comprising the steps of:
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deriving in-phase and quadrature data signals via a homodyne reception system; and applying a corrective function to the in-phase and quadrature data signals, the corrective function modifying the in-phase and quadrature data signals in a manner that precisely counteracts effects of chromatic dispersion on the in-phase and quadrature components of the optical data signal.
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15. A method of correcting in-phase and quadrature data signals for effect of chromatic dispersion prior to modulation onto an optical data signal, comprising the steps of:
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providing an in-phase data signal on a first input and providing a quadrature data signal on a second input; and applying a corrective function to the in-phase and quadrature data signals, the corrective function modifying the in-phase and quadrature data signals in a manner that precisely counteracts effects of chromatic dispersion occurring when the in-phase and quadrature data signals are modulated onto the optical data signal and transmitted across optical fiber.
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16. A receiver for receiving and processing an optical data signal, the optical data signal including at least two data bands and at least one side carrier, each of the at least two data bands including a pair of quadrature modulated data signals, the receiver comprising:
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a side carrier boosting module, the side carrier boosting module for increasing an amplitude of the at least one side carrier relative to the at least two data bands; a side carrier shifting module coupled to the side carrier boosting module, the side carrier shifting module for shifting the at least one side carrier into at least two shifted carriers, each of the at least two shifted carriers shifted to a center of one of the at least two data bands; and a chromatic dispersion compensation stage, the chromatic dispersion stage receiving as input in-phase and quadrature-phase signals of the quadrature modulated data signals, the chromatic dispersion correction stage including; a first splitter for splitting the input in-phase signal into a first branch and a second branch; a first COS circuit coupled to the first splitter for applying a COS transfer function to the in-phase signal in the first branch; a first SIN circuit coupled to the first splitter for applying a first SIN transfer function to the in-phase signal in the second branch; a second splitter for splitting the input quadrature-phase signal into a first quadrature branch and a second quadrature branch; an inverter coupled to the second quadrature branch for changing the phase of the quadrature signal in the second branch 180 degrees; a second COS circuit coupled to the first splitter for applying a COS transfer function to the quadrature signal in the first branch; a second SIN circuit coupled to the first splitter for applying a SIN transfer function to the quadrature signal in the second branch; a first combiner for combining output from the first SIN circuit with output from the second COS circuit into a corrected quadrature output signal; and a second combiner for combining output from the first COS circuit with output from the second SIN circuit into a corrected in-phase output signal.
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Specification