Abstract: Spatial division multiplexing (SDM) allows multiple optical signals to be multiplexed onto a single optical link. Performance of SDM systems may be improved by monitoring performance metrics indicative of crosstalk between the spatially multiplexed signals and adjusting at least one transmission characteristic of one or more of the multiplexed signals in order to reduce the impact of the intermodal crosstalk.

Abstract: A system and method are presented for coupling OAM optical beams to optical fibers. The system may include, for instance, an OAM beam generator, for receiving one or more of a plurality of input signals, and generating a different OAM mode signal for each input signal. The OAM beam generator may further be operative to adjust a location and/or an exit angle of the one or more OAM mode signals before sending the one or more OAM mode signals to a beam combiner that combines the one or more OAM mode signals into a combined mode OAM transmission. The system may further include a controller in communication with at least one crosstalk estimate sensor and the at least one OAM beam generator, the controller operative to optimize the crosstalk estimate by receiving the crosstalk estimate for one of the OAM mode signals, and sending control instructions instructing the OAM beam generator to adjust a location and/or an exit angle of the one or more OAM mode signals to reduce the crosstalk estimate.

Abstract: A state of polarization (SOP) controller allows a randomly polarized input beam to be converted to a single linear polarization, while transferring substantially all of the power to the output. The input beam is split into orthogonal components and one of the components rotated and a phase difference between the components compensated for. The phase aligned components may then be recombined into a single output. The phase shifters may be reset during a reset period during which the impact on data transmission is reduced.

Abstract: Aspects of the disclosure provided systems and methods which mitigate negative effects of Spectral Hole Burning when spectral changes are made. Embodiments of the disclosure are directed to methods and systems which preform spectral holes for the range of wavelength channels expected to be used in the optical communication system. In some embodiments this is achieved by controlling the network to ensure optical power is provided at each of a set of idle tone wavelengths distributed across the spectral band used in the optical communication system. In some embodiments a routing and spectrum assignment function satisfies new service requests while maintaining power to the set of idle tone wavelength functions. In some embodiments a network control function configures Reconfigurable Optical Add/Drop Multiplexers to broadcast idle tone wavelengths to provide power to each idle tone in each section.

Abstract: A method for assigning a network path after receiving a connection request to connect a first node with a second node of a network. The method including evaluating a network utilization parameter of the network, such as a network load or blocking probability, at that point in time. If the network utilization parameter is below a minimum threshold level, the method includes carrying out the steps of identifying a set of n network paths through the network that connect the first node with the second node and are absent non-linear links, performing network path selection by selecting p network paths from the set of n network paths that have the best linear OSNR, and, selecting a network path from the set of p network paths that balances the wavelength utilization between the first node and the second node of a network.

Abstract: Transmitter, receiver, system and method for secure data communications are provided. The transmitter receives an optical signal from a signal source and transmits first and second version of the optical signal in first and second areas of an optical channel. The receiver receives first and second components of an obfuscated signal and modifies the first component before combining the modified first component and the second component to obtain a recovered optical signal.

Abstract: A state of polarization (SOP) controller allows a randomly polarized input beam to be converted to a single linear polarization, while transferring substantially all of the power to the output. The input beam is split into orthogonal components and one of the components rotated and a phase difference between the components compensated for. The phase aligned components may then be recombined into a single output. The phase shifters may be reset during a reset period during which the impact on data transmission is reduced.

Abstract: Aspects of the present disclosure involve coherently mixing information in a first optical signal with information from one or more other optical signals, the optical signals being synchronous, to generate a mixed optical signal that obfuscates the information of the first optical signal. Each of the other optical signals is likewise mixed with a combination of the first and/or other optical signals resulting in a collection of mixed optical signals, none of which resemble the original first and other optical signals. When each of the mixed optical signals is transmitted in a separate optical fiber, then eavesdropping on only a single fiber cannot yield an unambiguous recovery of any one of the original optical signals.

Abstract: A system and method for obfuscating an optical signal is disclosed. Obfuscating the optical signal may make it more difficult for the optical signal to be detected by an interloper. In one embodiment, an optical signal is received at an optical transmitter, and an obfuscated optical signal is generated by performing a modification of the received optical signal. The obfuscated optical signal is then transmitted from the optical transmitter to an optical receiver. An at least partially deobfuscated optical signal is generated at the optical receiver by performing a modification of the obfuscated optical signal. The modification performed at the optical receiver corresponds to the modification performed at the optical transmitter.

Abstract: Methods and apparatus for add-drop multiplexing in all optical networking are provided. A tunable optical filter is controlled to drop a first portion of an incoming optical signal in a first wavelength band and pass a second portion of the incoming optical signal in a second wavelength band. The dropped first portion is distributed among local drop optical output ports with a demultiplexer. A multiplexer combines local add optical input signals in a third wavelength band into an add optical input signal and the tunable optical filter is controlled to add the add optical input signal to the passed second portion of the incoming optical signal. The tunable optical filter is configured to lower an optical loss for the passed second portion of the incoming optical signal at the account of a corresponding increase of an optical loss in the dropped first portion and/or the add optical input signal.

Abstract: Routing of optical paths through an optical network may account for both linear and non-linear effects of the physical layer when determining the route. The non-linear effects may be determined only as necessary, allowing the non-linear effects to be included in the routing determination for larger optical networks.

Abstract: Control apparatus and methods for photonic devices are disclosed. One or more detectors is used to monitor a functional state of a photonic device. Each detector is configured to receive a respective pair of optical signals from the photonic device and generate a detection signal proportional to a difference between the pair of optical signals. A controller generates control signal(s) for the photonic device based on the detection signal(s). The apparatus and methods may be used in optical switching applications to control multiple photonic devices configured as optical switches in order to implement a multi-channel optical switch fabric for a multi-channel optical switch.

Abstract: An optical device comprises a transmitter module, a receiver module, and a switch comprising a first port coupled to the transmitter module, a second port coupled to the receiver module, a third port configured to couple to a transmitter fiber, and a fourth port configured to couple to a receiver fiber. A method implemented in a switch, the method comprising operating in a monitor mode that provides for monitoring of a transmitter fiber or a receiver fiber, receiving a command to transition from the monitor mode to a data mode, connecting a transmitter module to the transmitter fiber, and connecting a receiver module to the receiver fiber.

Abstract: A method of analysing performance of an optical fiber link. As a preliminary step, a reference trace indicative of a distributed optical performance of the optical fiber link is derived. During in-service operation of the optical fiber link, an Optical Time Domain Reflectometry (OTDR) sub-system measures an OTDR trace with Raman amplification ON, and a real-time cumulative Raman Gain profile of the optical fiber link is calculated based on the reference trace and the measured OTDR trace.

Abstract: A method, a controller, and an optical section include performing an analysis to determine an amount of power offset on any in-service channels in an optical section due to a capacity change with a channel; defining a step size to ensure the capacity change does not exceed an offset limit based on the analysis; performing the capacity change in one or more iterations using the step size to limit the capacity change; and performing an optimization between each of the one or more iterations to adjust amplifier gains in the optical section to compensate for offsets on the in-service channels caused by a previous iteration.

Abstract: A method of analysing performance of an optical fiber link. As a preliminary step, a reference trace indicative of a distributed optical performance of the optical fiber link is derived. During in-service operation of the optical fiber link, an Optical Time Domain Reflectometry (OTDR) sub-system measures an OTDR trace with Raman amplification ON, and a real-time cumulative Raman Gain profile of the optical fiber link is calculated based on the reference trace and the measured OTDR trace.

Abstract: A method, a controller, and an optical section include performing an analysis to determine an amount of power offset on any in-service channels in an optical section due to a capacity change with a channel; defining a step size to ensure the capacity change does not exceed an offset limit based on the analysis; performing the capacity change in one or more iterations using the step size to limit the capacity change; and performing an optimization between each of the one or more iterations to adjust amplifier gains in the optical section to compensate for offsets on the in-service channels caused by a previous iteration.