Abstract: In accordance with an embodiment of the present disclosure a method for adaptively spacing channels of an optical network comprises determining a first desired power level of a first channel of an optical network. The method further comprises determining a second desired power level of a second channel of the optical network, the second desired power level being less than the first desired power level. Additionally, the method comprises determining a first spectral space between the first channel and one or more channels neighboring the first channel based at least on the first desired power level. The method also comprises determining a second spectral space between the second channel and one or more channels neighboring the second channel based at least on the second desired power level, the second spectral space less than the first spectral space.

Abstract: In accordance with the present disclosure a system for reducing polarization dependent loss (PDL) of an optical signal comprises a delay module coupled to one or more PDL inducing network elements of an optical network. The delay module is configured to time interleave a first polarization component with respect to a second polarization component of the optical signal. The time interleaving reduces interference caused by cross-talk components associated with the first and second polarization components and induced by the PDL of the PDL inducing elements.

Abstract: A method is provided for reducing polarization dependent loss experienced by an optical signal comprises monitoring a power level of a polarization multiplexed optical signal. The method further comprises detecting a power spike based on the monitored power. The power spike is induced by misalignment of a polarization component axis of the optical signal with a polarization dependent loss (PDL) axis of one or more network elements. The method further comprises rotating the polarization orientation of the optical signal such that the power spike is reduced.

Abstract: Methods and systems are provided for cancellation of chromatic dispersion combined laser phase noise. A method may include measuring a differential of laser phase noise using two optical pilot signals, the pilot signals each having a different optical frequency, or using an optical carrier and a pilot signal. The method may also include determining an approximate laser phase noise present in an optical system based on the measured differential of laser phase noise. The method may further include compensating for laser phase noise based on the determined approximate laser phase noise.

Abstract: A method for compensating for optical dispersion includes receiving an optical signal at a first node of an optical network that includes a first set of channels and a second set of channels that are each configured to be received using coherent digital receivers at a second node of the optical network. Each coherent digital receiver provides electronic dispersion compensation for the received channel at the second node. The method also includes forwarding the first set of channels from the first node without performing optical dispersion compensation on those channels. Furthermore, the method includes compensating for optical dispersion in the second set of channels at the first optical node and forwarding those channels from the first node. The optical dispersion compensation on the second set of channels at the first node provides dispersion compensation in addition to the compensation provided by the associated coherent digital receivers at the second node.

Abstract: A transmitter modulator that is operable to modulate signals according to multiple modulation formats includes a first modulator, a second modulator, and a polarization beam combiner. The first modulator encodes a first signal according to a first modulation format. The second modulator encodes a second signal according to a second modulation format, the first signal orthogonally polarized with respect to the second signal. The polarization beam combiner combines the first signal and the second signal for transmission.

Abstract: In accordance with an embodiment of the present disclosure a method for adaptively spacing channels of an optical network comprises determining a first desired power level of a first channel of an optical network. The method further comprises determining a second desired power level of a second channel of the optical network, the second desired power level being less than the first desired power level. Additionally, the method comprises determining a first spectral space between the first channel and one or more channels neighboring the first channel based at least on the first desired power level. The method also comprises determining a second spectral space between the second channel and one or more channels neighboring the second channel based at least on the second desired power level, the second spectral space less than the first spectral space.

Abstract: A method for reducing cross-phase modulation in an optical signal includes receiving an optical signal comprising a plurality of channels, wherein the information being communicated in a first set of one or more of the channels is modulated using one or more single-polarization modulation techniques and wherein the information being communicated in a second set of one or more of the channels is modulated using one or more dual-polarization modulation techniques. The method also includes splitting the optical signal into at least a first copy of the optical signal and a second copy of the optical signal and terminating the second set of channels in the first copy. Furthermore, the method includes applying a differential group delay to the second copy, the differential group delay introducing a walk-off between symbols communicated in a first polarization component of the second set of channels and the symbols of a second polarization component of the second set of channels.

Abstract: In accordance with embodiments of the present disclosure, a method for compensation of noise in an optical device is provided. The method may include calculating noise present in an optical carrier signal. The method may also include generating quadrature amplitude modulation input signals, the quadrature amplitude modulation input signals each including a term for compensation of the noise based on the calculated noise. The method may further include modulating the optical carrier signal to generate a modulated optical signal based on quadrature amplitude modulation input signals.

Abstract: In accordance with the present disclosure a system for reducing polarization dependent loss (PDL) of an optical signal comprises a delay module coupled to one or more PDL inducing network elements of an optical network. The delay module is configured to time interleave a first polarization component with respect to a second polarization component of the optical signal. The time interleaving reduces interference caused by cross-talk components associated with the first and second polarization components and induced by the PDL of the PDL inducing elements.

Abstract: In accordance with the present disclosure a method for reducing polarization dependent loss experienced by an optical signal comprises monitoring a power level of a polarization multiplexed optical signal. The method further comprises detecting a power spike based on the monitored power. The power spike is induced by misalignment of a polarization component axis of the optical signal with a polarization dependent loss (PDL) axis of one or more network elements. The method further comprises rotating the polarization orientation of the optical signal such that the power spike is reduced.

Abstract: Methods and systems are provided for cancellation of chromatic dispersion combined laser phase noise. A method may include measuring a differential of laser phase noise using two optical pilot signals, the pilot signals each having a different optical frequency, or using an optical carrier and a pilot signal. The method may also include determining an approximate laser phase noise present in an optical system based on the measured differential of laser phase noise. The method may further include compensating for laser phase noise based on the determined approximate laser phase noise.

Abstract: In one embodiment, a method for receiving optical signals includes receiving a first set of one or more signals and a second set of one or more signals, determining a block length used to process the first set of signals, and processing the first set of signals using the block length. The first set of signals and the second set of signals are separated by a guard band. The block length is based upon the width of the guard band.

Abstract: According to particular embodiments, reducing cross-phase modulation includes sending instructions to a phase modulation array comprising channel pixel sets that modulate phases of channels. The channel pixel sets comprise a first channel pixel set that modulates a first phase of a first channel and a second channel pixel set that modulates a second phase of a second channel that uses a phase modulation format. The first channel pixel set is instructed to modulate the first phase at a first constant phase. The second channel pixel set is instructed to modulate the second phase at a second constant phase different from the first constant phase in order to create a group delay between the first channel and the second channel.

Abstract: A method for reducing cross-phase modulation in an optical signal includes receiving an optical signal comprising a plurality of channels, wherein the information being communicated in a first set of one or more of the channels is modulated using one or more single-polarization modulation techniques and wherein the information being communicated in a second set of one or more of the channels is modulated using one or more dual-polarization modulation techniques. The method also includes splitting the optical signal into at least a first copy of the optical signal and a second copy of the optical signal and terminating the second set of channels in the first copy. Furthermore, the method includes applying a differential group delay to the second copy, the differential group delay introducing a walk-off between symbols communicated in a first polarization component of the second set of channels and the symbols of a second polarization component of the second set of channels.

Abstract: A method for compensating for optical dispersion includes receiving an optical signal at a first node of an optical network that includes a first set of channels and a second set of channels that are each configured to be received using coherent digital receivers at a second node of the optical network. Each coherent digital receiver provides electronic dispersion compensation for the received channel at the second node. The method also includes forwarding the first set of channels from the first node without performing optical dispersion compensation on those channels. Furthermore, the method includes compensating for optical dispersion in the second set of channels at the first optical node and forwarding those channels from the first node. The optical dispersion compensation on the second set of channels at the first node provides dispersion compensation in addition to the compensation provided by the associated coherent digital receivers at the second node.

Abstract: A method is provided for dispersion compensation of an optical signal communicated in an optical network comprising a plurality of spans of low chromatic dispersion fiber. The method includes receiving an optical signal comprising a plurality of channels, where the information communicated in a first set of one or more of the channels is modulated using a first modulation technique and where the information communicated in a second set of one or more of the channels is modulated using a second modulation technique. The method also includes uniformly undercompensating for optical dispersion in the optical signal across all of the channels of the optical signal such that the accumulated dispersion in the optical signal increases with each span over which the optical signal is communicated. In particular embodiments, all of the channels of the optical signal are uniformly undercompensated in the range of approximately 60% to approximately 85% dispersion compensation for each span.

Abstract: According to particular embodiments, reducing cross-phase modulation includes sending instructions to a phase modulation array comprising channel pixel sets that modulate phases of channels. The channel pixel sets comprise a first channel pixel set that modulates a first phase of a first channel and a second channel pixel set that modulates a second phase of a second channel that uses a phase modulation format. The first channel pixel set is instructed to modulate the first phase at a first constant phase. The second channel pixel set is instructed to modulate the second phase at a second constant phase different from the first constant phase in order to create a group delay between the first channel and the second channel.

Abstract: A system for cross-phase-modulation-noise reduced transmission in hybrid networks includes a first, second, and third set of optical transmitters. The first set of optical transmitters transmits a set of ten gigabit per second signals. The second set of optical transmitters transmits a set of forty gigabit per second signals. The third set of optical transmitters transmits a set of one hundred gigabit per second signals. On a wavelength spectrum, the set of 10 G signals is immediately adjacent to the set of 100 G signals, and the set of 100 G signals is immediately adjacent to the set of 40 G signals. The set of 10 G signals and the set of 100 G signals are not separated by a guard band. In addition, the set of 100 G signals and the set of 40 G signals are also not separated by a guard band.

Abstract: A system operable to demodulate a PSK-ASK encoded signal encoded according to ASK modulation and PSK modulation includes one or more inversion modulators. An inversion modulator receives an ASK-decoded signal generated according to a first signal split from the PSK-ASK encoded signal. The inversion modulator includes an inverter and an amplitude modulator. The inverter inverts the ASK-decoded signal to yield an inverted ASK-decoded signal, and the amplitude modulator modulates a second signal split from the PSK-ASK encoded signal according to the inverted ASK-decoded signal prior to PSK demodulation.