Consistent with the present disclosure, data, in digital form, is received by a transmit node of an optical communication system, and converted to an analog signal by a digital-to-analog converter (DAC) to drive a modulator. The modulator, in turn, modulates light at one of a plurality of wavelengths in accordance with the received data forming a plurality of corresponding carriers. The carriers are modulated according to one of a plurality of modulation formats and then optically combined to form a superchannel of a constant maximum capacity, for example. Accordingly, the number of carriers and the bit rate for each carrier remain constant for each modulation format to realize a constant maximum capacity. The superchannel is then transmitted over an optical communication path to a receive node. At the receive node, the superchannel is optically demultiplexed from a plurality of other superchannels. The plurality of carriers of the superchannel are then supplied to a photodetector circuit, which receives additional light at one of the optical signal carrier wavelengths from a local oscillator laser. An analog-to-digital converter (ADC) is provided in the receive node to convert the electrical signals output from the photodetector into digital form. The output from the ADC is then filtered in the electrical domain, such that optical demultiplexing of the carriers is unnecessary.

A data center network includes a plurality of packet-optical switches each at a location in the data center network and each including a switch fabric comprising both a Layer 1 fabric and a packet fabric communicatively coupled to one or more line ports; wherein the plurality of packet-optical switches are communicatively coupled to one another in a topology to form data connectivity in the data center network, and wherein each of the plurality of packet-optical switches is configured to provide the data connectivity through the Layer 1 switch bypassing the packet fabric when the location does not require Layer 2 forwarding in the topology, and provide the data connectivity through the Layer 1 switch and using the packet fabric to provide the data service with multi-point connectivity when the location requires Layer 2 forwarding in the topology.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

A system includes an optical fiber cross-connect module with upstream ports and downstream ports, a first set of optical fibers connected from optical line terminals to the upstream ports, and a second set of optical fibers connected to the downstream ports and a customer optical network unit. The optical line terminals provide multiple wavelengths carrying optical signals at different bitrates over the first set of optical fibers. The customer optical network unit includes a tunable filter configured to receive any one of the multiple wavelengths. The optical fiber cross-connect module divides the optical signals received at each of the upstream ports into each of the downstream ports, and the customer optical network unit may be tuned to pass through a particular wavelength from the multiple wavelengths.

In an optical network based on a dense wavelength division multiplexing system using a flexible frequency grid, it is difficult to improve the usage efficiency of an optical frequency band owing to the occurrence of fragmentation of the optical frequency band; therefore, an optical network controller according to an exemplary aspect of the present invention includes an optical frequency region setting means for dividing an optical frequency band used in an optical network based on a dense wavelength division multiplexing system using a flexible frequency grid, and setting a plurality of optical frequency regions; and an optical path setting means for setting optical paths having a common attribute in at least one of the plurality of optical frequency regions.

A system includes an optical fiber cross-connect module with upstream ports and downstream ports, a first set of optical fibers connected from optical line terminals to the upstream ports, and a second set of optical fibers connected to the downstream ports and a customer optical network unit. The optical line terminals provide multiple wavelengths carrying optical signals at different bitrates over the first set of optical fibers. The customer optical network unit includes a tunable filter configured to receive any one of the multiple wavelengths. The optical fiber cross-connect module divides the optical signals received at each of the upstream ports into each of the downstream ports, and the customer optical network unit may be tuned to pass through a particular wavelength from the multiple wavelengths.

Validating a path in an optical layer of a communications network, for client traffic having an associated service level, involves setting an optical quality margin according to the service level associated with that client traffic. The optical quality margin indicates how close an estimated optical quality of the path can approach a level which produces a threshold error rate. This margin is used to check whether the estimated optical quality is within the optical quality margin set according to the client traffic service level. Making the optical quality margin dependent on client traffic service level, can enable increased optical reach. This can give more flexibility in path selection and enable better matching to service levels of client traffic.

The example embodiments presented herein are directed towards an Optical Network Element, ONE, node (14), and corresponding method therein, for establishing multiple spectral routing in an optical transport network. The establishment of the multiple spectral routing features the use of a Split-Spectrum Label, SSL, (11) which comprises multiple definitions for spectral slots, where each definition has an absolute starting and an absolute ending frequency allocation.

A routing and wavelength assignment method for use in an optical fiber network includes (i) identifying a path between each node pair in the network, (ii) identifying a block of spectral resource within the spectrum band of the identified path of a selected node pair, (iii) calculating a spectrum entropy value of the identified path of the selected node pair based on a logarithm of the ratio of the number of wavelength channels in each of the one or more blocks, to the total number of wavelength channels across the spectrum band, (iv) iterating (ii) and (iii) in respect of each of the paths between each other node pair in the network, until a spectrum entropy value of all the paths between all the node pairs has been calculated, (v) summing the spectrum entropy value of all of the paths between all of the node pairs to obtain a network spectrum entropy value in respect of a network configuration based on the paths between the node pairs, and (vi) determining from the network spectrum entropy value whether a signal carrying a demand through the network is separated from any other signals by a spectral gap sufficient to accommodate a change in the demand to an expected level.

A method of statistical multiplexing with one of Layer 0 Flexible Grid optical spectrum and Layer 1 Time Division Multiplexed (TDM) bandwidth in a multi-layer network includes obtaining a sampling of bandwidth usage over time on ports and links in the multi-layer network for one of Layer 0 and Layer 1 traffic using a plurality of statistical parameters, wherein the plurality of statistical parameters are defined for the one of Layer 0 and Layer 1 traffic; monitoring the plurality of statistical parameters; and triggering based on the monitoring one of i) adjustments to the one of Layer 0 and Layer 1 traffic and ii) adjustments to routing parameters on the links for new traffic, wherein the triggering is one of through a control plane and a Software Defined Networking (SDN) controller.