A network capable of being used in a datacenter is described. In some embodiments, the network can comprise a set of optical fiber rings, wherein each optical fiber ring carries data traffic on one or more wavelengths, and wherein each optical fiber ring is partitioned into multiple sectors. A reconfigurable optical add-drop multiplexer (ROADM) can be coupled to at least one optical fiber in each of at least two sectors. An electro-optical-switch can be coupled to each ROADM in each of the at least two sectors. A set of switches can be coupled to each electro-optical-switch in each of the at least two sectors. The set of switches can comprise a first layer of aggregation switches that is coupled to a second layer of edge switches, wherein the edge switches can be coupled to servers in a datacenter.

Processing a received optical signal in an optical communication network includes equalizing a received optical signal to provide an equalized signal, demodulating the equalized signal according to an m-ary modulation format to provide a demodulated signal, decoding the demodulated signal according to an inner code to provide an inner-decoded signal, and decoding the inner-decoded signal according to an outer code. Other aspects include other features such as equalizing an optical channel including storing channel characteristics for the optical channel associated with a client, loading the stored channel characteristics during a waiting period between bursts on the channel, and equalizing a received burst from the client using the loaded channel characteristics.

A method may include transmitting, by an optical device, a first channel. The first channel may have a first set of subcarriers. The first channel may be attenuated during transmission by a filter associated with a wavelength selective switch. The method may further include transmitting, by the optical device, a second channel. The second channel may have a second set of subcarriers. The second channel may be attenuated during transmission by the filter associated with the wavelength selective switch. The first channel and the second channel being included in a super-channel. The first set of subcarriers may be selected based on a first signal quality factor associated with attenuation of the first set of subcarriers by the filter. The second set of subcarriers may be selected based on a second signal quality factor associated with attenuation of the second set of subcarriers by the filter.

The invention relates to a system for sending data in an optical network comprising source nodes (1-1, 1-2, 1-3, 1-4, 1-5), each capable of generating, in a spectral band that is associated with it, a multi-carrier optical data signal obtained by modulation of a source signal at a source wavelength and of sending this signal in the form of single-band data bursts (11-13, 21-23, 31-33, 41-43, 51-53) that can be associated with distinct source wavelengths, and a combiner (1,2) for combining single-band data bursts, sent by the source nodes in the spectral bands that are associated with them, into multi-band data bursts (61-63, 71-73) occupying a spectral band corresponding to a juxtaposition of the spectral bands associated with the source nodes. In this system, a unit for controlling an instant of sending of said single-band data bursts by the source nodes, implements a control plane taking account of a path time of the single-band data bursts sent by the source nodes to the combiner.

An optical transmitter includes: an optical modulator including a pair of waveguides of a Mach-Zehnder interferometer to which signal light is input, and a plurality of optical phase shifters that are provided in each of the pair of waveguides and that each modulate a phase of the signal light with a plurality of drive signals; a plurality of drivers that generate the plurality of drive signals based on a plurality of digital signals corresponding to a symbol to which data signals are mapped and output the plurality of drive signals to the plurality of optical phase shifters, respectively; and a processor that shapes a waveform of the signal light such that a bandwidth of a spectrum of the signal light modulated by the optical modulator is equal to or less than a bandwidth corresponding to a rate of the symbol.

There is provided a transmission apparatus configured to receive a frequency-division multiplexed optical signal generated by modulating carrier light based on a plurality of frequency-division multiplexed subcarrier signals, the transmission apparatus including: a processor configured to: extract a plurality of subcarrier signals of the plurality of frequency-division multiplexed subcarrier signals from the frequency-division multiplexed optical signal; calculate signal qualities of the plurality of subcarrier signals; detect a deviation of the signal qualities between the plurality of subcarrier signals; and perform a frequency control of the carrier light generated by an optical source of a transmission apparatus configured to transmit the frequency-division multiplexed optical signal, based on the deviation of the signal qualities.

Optical network systems and components are disclosed including a transmitter comprising a digital signal processor receiving a plurality of independent data streams, the digital signal processor supplying outputs based on the plurality of independent data streams, the digital signal processor comprising a plurality of pulse shape filters corresponding to the plurality of independent data streams, the plurality of pulse shape filters configured to filter the independent data streams to produce a first subcarrier having a first frequency bandwidth and a second subcarrier having a second frequency bandwidth different than the first frequency bandwidth for the outputs.

We disclose an optical add-drop multiplexer that can apply different routing operations to different subcarriers of a data frame. In an example embodiment, the digital signal processor (DSP) of the optical add-drop multiplexer carries out subcarrier-specific add, drop, and pass-through operations in the electrical frequency domain, which enables the DSP to only partially unwrap the pass-through subcarriers, thereby at least partially avoiding some of the more processing-power-hungry DSP operations and reducing the sub-wavelength routing latency accordingly. Also disclosed is an example data-frame structure that can be used to provide subcarrier-specific routing instructions to the optical add-drop multiplexer.

A transmission device includes: a plurality of modulators that respectively generate multicarrier signals from given data; a distributor that distributes input data to the modulators; an optical circuit that multiplexes the multicarrier signals to generate a WDM optical signal; and a controller that obtains allocation information from a receiver of the WDM optical signal and generates a distribution instruction to control the distributor and a bit allocation instruction to control the modulators according to the allocation information. The allocation information is calculated based on transmission characteristics of each subcarrier of the respective multicarrier signals and the allocation information indicates a number of bits of data allocated to each of the subcarriers. The distributor distributes the input data to the modulators according to the distribution instruction. The modulators respectively allocate data distributed from the distributor to the subcarriers according to the bit allocation instruction to generate the multicarrier signals.

There is provided a tray which is connected to a plurality of transmitters that multicarrier-transmit a plurality of parallel signals by optical subcarriers. The framer selects time slots to be allocated to a path to be accommodated such that the number of optical subcarriers corresponding to the time slots satisfies a predetermined condition on the basis of empty time slots which are specified by path accommodation information indicating a correspondence between paths allocated to a client signal and time slots in a signal frame and the optical subcarriers corresponding to the empty time slots indicated by time slot information indicating a correspondence between the time slots and the optical subcarriers, and sets the selected time slot in the path accommodation information. The framer sets a client signal to the time slots on the basis of the path accommodation information.