Abstract: A method and apparatus for optimizing optical transport using a software defined network (SDN) controller are disclosed herein. The SDN controller may define a margin optimization function based on at least one optical system performance metric. The function may include at least one related initiation criterion. Further, the SDN controller may collect at least one measurement for the performance metric. The measurement may include an assessment of deployed carriers not carrying client data. The SDN controller may determine whether the initiation criterion is met based on at least one collected measurement. The SDN controller may select a system margin optimization mechanism and define a system margin optimization threshold criterion on a condition that the initiation criterion is met. The SDN controller may determine whether the optimization threshold criterion is met. The SDN controller may implement one or more optimization events on a condition that the optimization threshold criterion is met.

Abstract: A method and apparatus for optimizing optical transport using a software defined network (SDN) controller are disclosed herein. The SDN controller may define a margin optimization function based on at least one optical system performance metric. The function may include at least one related initiation criterion. Further, the SDN controller may collect at least one measurement for the performance metric. The measurement may include an assessment of deployed carriers not carrying client data. The SDN controller may determine whether the initiation criterion is met based on at least one collected measurement. The SDN controller may select a system margin optimization mechanism and define a system margin optimization threshold criterion on a condition that the initiation criterion is met. The SDN controller may determine whether the optimization threshold criterion is met. The SDN controller may implement one or more optimization events on a condition that the optimization threshold criterion is met.

Abstract: The present disclosure provides systems and methods for channel power offsets for multi-rate dense wave division multiplexed (DWDM) transmission over optical add-drop multiplexers (OADMs). The present invention includes algorithms to set power levels of each type of channel in different sections of a fiber system to optimize the performance of that type of channel at the receiver. For example, the present invention can optimize power levels based on different channel modulation formats, bit rates, channel spacings, and the like. Advantageously, the present invention improves the total capacity (bit rate) and reach that channels of a given bit rate can achieve, and maximizes the reach of channels without sacrificing capacity.

Abstract: The present disclosure provides polarization mode dispersion compensation (PMDC) and polarization de-multiplexing systems and methods for polarization multiplexed (PolMux) optical transmission systems. The PMDC detects an error signal before a polarization splitter in PolMux systems for controlling polarization controllers (PC) and/or DGDs in the PMDC for return-to-zero (RZ) differential m-phase shift keying (DmPSK) signals. For bit-aligned PolMux systems, the error signal could be the level of clock frequency at one, two, or more times of the baud rate at one polarization. For bit-interleaved PolMux systems, the error signal could be the level of clock frequency at two times of the baud rate at one polarization. The PMDC can operate in PolMux systems with any arbitrary time offset between the two polarizations. The polarization de-multiplexer utilizes error detection at both output arms of a polarization splitter to mitigate PDL impact on any PolMux type of signal.

Abstract: The present disclosure provides systems and methods for channel power offsets for multi-rate dense wave division multiplexed (DWDM) transmission over optical add-drop multiplexers (OADMs). The present invention includes algorithms to set power levels of each type of channel in different sections of a fiber system to optimize the performance of that type of channel at the receiver. For example, the present invention can optimize power levels based on different channel modulation formats, bit rates, channel spacings, and the like. Advantageously, the present invention improves the total capacity (bit rate) and reach that channels of a given bit rate can achieve, and maximizes the reach of channels without sacrificing capacity.

Abstract: The present disclosure provides polarization mode dispersion compensation (PMDC) and polarization de-multiplexing systems and methods for polarization multiplexed (PolMux) optical transmission systems. The PMDC detects an error signal before a polarization splitter in PolMux systems for controlling polarization controllers (PC) and/or DGDs in the PMDC for return-to-zero (RZ) differential m-phase shift keying (DmPSK) signals. For bit-aligned PolMux systems, the error signal could be the level of clock frequency at one, two, or more times of the baud rate at one polarization. For bit-interleaved PolMux systems, the error signal could be the level of clock frequency at two times of the baud rate at one polarization. The PMDC can operate in PolMux systems with any arbitrary time offset between the two polarizations. The polarization de-multiplexer utilizes error detection at both output arms of a polarization splitter to mitigate PDL impact on any PolMux type of signal.

Abstract: Chromatic dispersion in a high speed CS-RZ WDM transmission system is reduced by providing tailored “precompensation” for individual and/or groups of optical signals. Such precompensation is achieved by passing the optical signals through a dispersion compensating elements, such as dispersion compensating fiber, within an optical multiplexer, i.e., prior to multiplexing the signals onto a single optical fiber. Additional dispersion compensation can be performed in optical amplifiers and within an optical demultiplexer downstream from the optical multiplexer.

Abstract: A method and apparatus for controlling phase alignment in a modulator of a transmitter in an optical communications system utilizes an RF power signature to tune phase alignment. A portion of the optical signal is tapped and converted to an electrical signal. An electrical band-pass filter and RF detector examines a narrow slice of the RF spectrum and utilize the detected RF power to control phase alignment between the data modulator and pulse carver. Another portion of the optical signal is multiplied by the pulse carver clock, filtered and integrated in order to generate a second phase control signal for controlling the relative phase of a dual arm modulator being used as the pulse carver in one embodiment.

Abstract: A system for the bidirectional application of a dispersion compensating module in a regional system includes a dispersion compensating module configured to receive a first optical signal traveling along a first path and a second optical signal traveling along a second path, wherein the dispersion compensating module provides dispersion compensation to the first optical signal and the second optical signal. The system also includes a first circulator in optical communication with the dispersion compensating module and the first path, wherein the first circulator delivers the first optical signal to the dispersion compensating module. The system further includes a second circulator in optical communication with the dispersion compensating module and the second path, wherein the second circulator delivers the second optical signal to the dispersion compensating module.

Abstract: An optical communication device, and related method, are provided for reducing ripple in WDM systems. In particular, the optical communication device includes a dynamic gain equalization (DGE) circuit is coupled to an optical communication path carrying the WDM optical signals. The DGE circuit adjusts the powers associated with each channel on a channel-by-channel basis so that the WDM optical signal has a desired power spectrum. The DGE is controlled in response to sense signals generated by an optical performance monitoring (OPM) circuit located downstream from the DGE or substantially co-located with the DGE. The OPM monitors the WDM spectrum for optical signal power variations and outputs the sense signal when the variations fall outside a given tolerance. Typically, one DGE is associated with a group of concatenated amplifiers so that multiple DGEs are provided in a system having many groups of such amplifiers.

Abstract: An optical communication device, and related method, are provided for reducing ripple in WDM systems. In particular, the optical communication device includes a dynamic gain equalization (DGE) circuit is coupled to an optical communication path carrying the WDM optical signals. The DGE circuit adjusts the powers associated with each channel on a channel-by-channel basis so that the WDM optical signal has a desired power spectrum. The DGE is controlled in response to sense signals generated by an optical performance monitoring (OPM) circuit located downstream from the DGE or substantially co-located with the DGE. The OPM monitors the WDM spectrum for optical signal power variations and outputs the sense signal when the variations fall outside a given tolerance. Typically, one DGE is associated with a group of concatenated amplifiers so that multiple DGEs are provided in a system having many groups of such amplifiers.

Abstract: An optical communication device, and related method, are provided for reducing ripple in WDM systems. In particular, the optical communication device includes a dynamic gain equalization (DGE) circuit is coupled to an optical communication path carrying the WDM optical signals. The DGE circuit adjusts the powers associated with each channel on a channel-by-channel basis so that the WDM optical signal has a desired power spectrum. The DGE is controlled in response to sense signals generated by an optical performance monitoring (OPM) circuit located downstream from the DGE or substantially co-located with the DGE. The OPM monitors the WDM spectrum for optical signal power variations and outputs the sense signal when the variations fall outside a given tolerance. Typically, one DGE is associated with a group of concatenated amplifiers so that multiple DGEs are provided in a system having many groups of such amplifiers.

Abstract: An optical communication device, and related method, are provided for reducing ripple in WDM systems. In particular, the optical communication device includes a dynamic gain equalization (DGE) circuit is coupled to an optical communication path carrying the WDM optical signals. The DGE circuit adjusts the powers associated with each channel on a channel-by-channel basis so that the WDM optical signal has a desired power spectrum. The DGE is controlled in response to sense signals generated by an optical performance monitoring (OPM) circuit located downstream from the DGE or substantially co-located with the DGE. The OPM monitors the WDM spectrum for optical signal power variations and outputs the sense signal when the variations fall outside a given tolerance. Typically, one DGE is associated with a group of concatenated amplifiers so that multiple DGEs are provided in a system having many groups of such amplifiers.

Abstract: A method and apparatus for controlling phase alignment in a modulator of a transmitter in an optical communications system utilizes an RF power signature to tune phase alignment. A portion of the optical signal is tapped and converted to an electrical signal. An electrical band-pass filter and RF detector examines a narrow slice of the RF spectrum and utilize the detected RF power to control phase alignment between the data modulator and pulse carver. Another portion of the optical signal is multiplied by the pulse carver clock, filtered and integrated in order to generate a second phase control signal for controlling the relative phase of a dual arm modulator being used as the pulse carver in one embodiment.

Abstract: Chromatic dispersion in a high speed CS-RZ WDM transmission system is reduced by providing tailored “precompensation” for individual and/or groups of optical signals. Such precompensaiton is achieved by passing the optical signals through a dispersion compensating elements, such as dispersion compensating fiber, within an optical multiplexer, i.e., prior to multiplexing the signals onto a single optical fiber. Additional dispersion compensation can be performed in optical amplifiers and within an optical demultiplexer downstream from the optical multiplexer.

Abstract: Consistent with the present invention, in-fiber Bragg gratings are used to demultiplex optical signals in a WDM optical communication system. The in-fiber Bragg gratings also perform dispersion compensation of the selected optical signals. As a result, additional segments of DCF for further dispersion compensation are rendered unnecessary. Improved performance is thus achieved with an inexpensive and simplified system design.

Abstract: An exemplary embodiment of the invention is an optical communications network transmitting signals on multiple wavelengths. The network includes a first dispersion compensating fiber providing dispersion compensation and dispersion slope compensation. The first dispersion compensating fiber has a first non-zero dispersion coefficient and a first non-zero dispersion slope coefficient. The network also includes a second dispersion compensating fiber in optical communication with the first dispersion compensating fiber. The second dispersion compensating fiber has a second non-zero dispersion coefficient and a second non-zero dispersion slope coefficient. The lengths of first dispersion compensating fiber and second dispersion compensating fiber are selected to compensate dispersion and compensate dispersion slope in a transmission path in optical communication with the first dispersion compensating fiber and the second dispersion compensating fiber.