A transmitter includes at least three tunable laser sources, an optical multiplexer, and a processor. The at least three tunable laser sources are configured to receive respective data streams, and to output respective Tx light beams at different respective carrier frequencies, modulated with the respective data streams. The optical multiplexer is configured to combine the multiple Tx light beams to produce a combined beam formed of the modulated Tx light beams at the different carrier frequencies, and to transmit the combined beam over an optical fiber. The processor is configured to receive a notification indicative of an interference occurring due to Four-Wave Mixing (FWM) in the optical fiber, and to modify at least one of the carrier frequencies responsively to the notification in order to mitigate the interference due to FWM.

Systems and methods are implemented at an Optical Add/Drop Multiplexer (OADM) node using virtual sections to provide sectional control over an optical link over a foreign-controlled optical network. The systems and methods include virtually splitting the optical link at a shelf processor associated with the OADM node; in a non-fault condition, obtaining and storing a power snapshot of the optical link and associated virtual sections thereon, from an optical spectrum monitor; responsive to a fault on one or more virtual sections of the virtual sections, obtaining a current power snapshot of the optical link and the associated virtual sections; and comparing the stored power snapshot and the current power snapshot of the one or more virtual sections and providing a fault alarm for the one or more virtual sections based on the comparing to a control plane for management thereof.

A plurality of optical signals are arranged on optical frequency grids having a frequency spacing of ?f, a wavelength multiplexing optical signal includes at least one specific arrangement signal group, and the specific arrangement signal group includes Q S signal(s) and R P signal(s), where Q is an integer of 1 or more and R is an integer of 1 or more. A frequency difference between any pair of S signals included in the specific arrangement signal group is different from frequency differences between all of other pairs of S signals and frequency differences between all pairs of P signals, and a frequency difference between any pair of P signals included in the specific arrangement signal group is different from frequency differences between all pairs of S signals and frequency differences between all of other pairs of P signals.

An optical communications apparatus includes a branching unit and a switching module. The branching unit is configured to be connected to first, second, and third optical cables each including an optical fiber. The branching unit includes a branch optical path configured to route a fixed pre-determined range of wavelengths that are input to the branching unit from the optical fiber of the first cable to the optical fiber of the third cable. The switching module includes at least one optical switch having a bypass configuration and a branch connecting configuration. In the bypass configuration, a connection via the branch optical path to a distal portion of the third cable is bypassed. In the branch connecting configuration, the branch optical path is enabled so that the pre-determined range of wavelengths that are input to the branching unit are routed to the optical fiber of the distal portion of the third cable.

A reconfigurable optical add/drop multiplexer using a wavelength selective switch (WSS) component to multiplex wavelength channels into a wavelength division multiplexed (WDM) signal. When a given channel is dropped, an amplified spontaneous emission (ASE) injection signal is multiplexed as a ghost channel into the WDM signal. The ASE injection channel can mitigate polarization hole burning and can provide a fuller power spectrum density. However, the ASE injection channel also defines a monitoring window. As an optical channel monitor (OCM) monitors the WDM signal, the OCM can detect, within the monitoring window, any underlying characteristic of the given wavelength channel. In this instance in response to the detected characteristic, the WSS component switches from multiplexing the ghost channel into the WDM signal to multiplexing the given wavelength channel into the WDM signal.

A telecommunications module includes an optical wavelength division multiplexer/demultiplexer configured to demultiplex a first optical signal input into the telecommunications module into a plurality of different wavelengths, a fiber optic splitter configured to split a second optical signal input into the telecommunication module into a plurality of optical signals, and a plurality of optical add/drop filters, each of the optical add/drop filters configured to combine one of the optical signals that has been split by the fiber optic splitter and one of the wavelengths that has been demultiplexed by the optical wavelength division multiplexer/demultiplexer into a combination output signal that is output from the telecommunications module.

A demultiplexing unit that is provided in an optical device and performs demultiplexing into a plurality of optical signals having wavelengths different from each other includes a plurality of optical filters that are coupled in multiple stages and in which a period of a peak wavelength of a transmission spectrum differs among different stages, a monitoring optical filter coupled to one of the plurality of optical filters, a monitoring photodetector coupled to the output side of the monitoring optical filter, and a plurality of wavelength adjustment units that are provided individually for the plurality of optical filters and the monitoring optical filter and cause wavelength shifts of an equal amount in a same direction.

Examples of a polarization independent optical device are described. One example polarization independent optical device includes an input/output preprocessing optical path and M add/drop optical paths. Any add/drop optical path can be configured to drop a first Q.sub.TE and a first P.sub.TE that meet a resonance condition of a microring included in the add/drop optical path such that each add/drop optical path can be configured to drop a desired optical signal. Any add/drop optical path can also be configured to transmit an input optical signal to the input/output preprocessing optical path. Therefore, when any of the M add/drop optical paths is configured to drop a desired optical signal, another add/drop optical path can be configured to add a desired optical signal.

An apparatus that includes one or more electrical or optical I/O ports that interface to external communication equipment, one or more optical ports that interface to an optical transport network that carries wavelength-division-multiplexed (WDM) optical signals, one or more tunable optical transceivers, and packet switching logic. The apparatus is configured to perform packet processing operations for ingress and egress data frames or packets. The apparatus can further include control circuitry that can take part in an automatic provisioning process that configures the tunable optical transceiver units of the network device, specifically configuring the optical channels/wavelengths of the optical signals that are transmitted by the tunable optical transceivers. The apparatus can also implement a method of processing and/or managing the optical channels/wavelengths of the optical signals that are transmitted by the tunable optical transceivers based upon the destination address of ingress data frames or packets. Multiple units can interface to the optical transport network for communication of optical packet data between the units over the optical transport network as described herein.

A telemetry manager receives, from a network server, global data collection information about network components in an optical network device. The global data collection information includes identifiers for network nodes in the network components from which telemetry data are to be collected, and reporting frequency and encoding format for sending collected telemetry data to the network server. The telemetry manager identifies, from the global data collection information, local data collection information specified for a network component, and sends this information to a telemetry agent in the network component. The telemetry manager receives telemetry data generated by a network node of the network component, where the data is provided according to instructions in the local data collection information. The telemetry manager converts the telemetry data from its native format to an encoding format specified by the global data collection information, and sends the encoded telemetry data to the network server.