If wavelength defragmentation is performed during the operation of an optical network, an instantaneous interruption of a network arises; consequently, data are lost; therefore, an optical network control method according to an exemplary aspect of the present invention includes monitoring a data volume of a client signal to be transmitted using a plurality of optical subcarriers; and performing synchronously, depending on a variation in the data volume, an optical subcarrier changing process of changing an active optical subcarrier, of the plurality of optical subcarriers, to be used for transmitting the client signal, and a remapping process of remapping the client signal onto an active optical subcarrier after having been changed.

Systems and methods include, responsive to a request for capacity change of X channels, X is an integer >1, on an optical section (14) and at an Optical Add/Drop Multiplexer (OADM) node (12) in an optical network (10), dividing optical spectrum on the optical section into M slots, M is an integer >1, such that the capacity change of X channels takes a maximum of N steps, N is an integer >1; and performing the capacity change of X channels in up to the N steps in an interleaved manner that changes a subset of the X channels in each of the N steps. For each step, the performing can include a maximum of M/N slots of the M slots with spacing between each of the M/N slots not used for the capacity change in a corresponding step. The spacing can be f, (N+f), (2N+f), . . . , M over the optical spectrum, where f is each step, f=1, 2, . . . , N.

If wavelength defragmentation is performed during the operation of an optical network, an instantaneous interruption of a network arises; consequently, data are lost; therefore, an optical network control method according to an exemplary aspect of the present invention includes monitoring a data volume of a client signal to be transmitted using a plurality of optical subcarriers; and performing synchronously, depending on a variation in the data volume, an optical subcarrier changing process of changing an active optical subcarrier, of the plurality of optical subcarriers, to be used for transmitting the client signal, and a remapping process of remapping the client signal onto an active optical subcarrier after having been changed.

A method and an apparatus for spectrum defragmentation, where the method includes: obtaining, by a transmit end, a target data stream; sending the target data stream on one line using a to-be-adjusted frequency band; adjusting, on another line, an occupied frequency band of the target data stream from the to-be-adjusted frequency band to a target frequency band; switching the target data stream to the other line; and transmitting the target data stream using the target frequency band.

Disclosed herein are multi-layer wavelength-division multiplexing (WDM) devices that include a first optical signal router to route first demultiplexed signals from a common layer to a first channel layer and a second optical signal router to route second demultiplexed signals from the common layer to a second channel layer.

Disclosed herein are multi-layer wavelength-division multiplexing (WDM) devices that include a first optical signal router to route first demultiplexed signals from a common layer to a first channel layer and a second optical signal router to route second demultiplexed signals from the common layer to a second channel layer.

There is presented an apparatus for use with a Wavelength Division Multiplexed Passive Optical Network (WDM-PON). The apparatus comprises an electronic controller, optical transmitters and a wavelength multiplexer. The electronic controller is configured to receive first input electrical data signals, output electrical data signals on data channels based upon the input electrical data signals and change the data rate of at least a first of the output electrical data signals. The optical transmitters, which receive the electrical data signals, are each configured to receive, respectively on different data channels, electrical data signals output from the electronic controller. The optical transmitters output light signals corresponding to the received electrical data signals from the electronic controller. Respective light signals of each optical transmitter are centred on a different wavelength to the light signals of the other optical transmitters. The wavelength multiplexer is configured to receive the output light signals from the optical transmitters and output a wavelength multiplexed optical output signal.

If wavelength defragmentation is performed during the operation of an optical network, an instantaneous interruption of a network arises; consequently, data are lost; therefore, an optical network control method according to an exemplary aspect of the present invention includes monitoring a data volume of a client signal to be transmitted using a plurality of optical subcarriers; and performing synchronously, depending on a variation in the data volume, an optical subcarrier changing process of changing an active optical subcarrier, of the plurality of optical subcarriers, to be used for transmitting the client signal, and a remapping process of remapping the client signal onto an active optical subcarrier after having been changed.

If wavelength defragmentation is performed during the operation of an optical network, an instantaneous interruption of a network arises; consequently, data are lost; therefore, an optical network control method according to an exemplary aspect of the present invention includes monitoring a data volume of a client signal to be transmitted using a plurality of optical subcarriers; and performing synchronously, depending on a variation in the data volume, an optical subcarrier changing process of changing an active optical subcarrier, of the plurality of optical subcarriers, to be used for transmitting the client signal, and a remapping process of remapping the client signal onto an active optical subcarrier after having been changed.

A method and an apparatus for spectrum defragmentation, where the method includes: obtaining, by a transmit end, a target data stream; sending the target data stream on one line using a to-be-adjusted frequency band; adjusting, on another line, an occupied frequency band of the target data stream from the to-be-adjusted frequency band to a target frequency band; switching the target data stream to the other line; and transmitting the target data stream using the target frequency band.