In an example method, network traffic transmitted between a plurality of network nodes via a communications network is monitored. Subsets of the network traffic are ranked according to one or more ranking criteria. A mesh network is deployed between the plurality of network nodes based on the ranking of the subsets of the network traffic. The mesh network includes a plurality of network links, where each network link communicatively couples a respective network node from among the plurality of network nodes to another respective network node from among the plurality of network nodes.

An example system includes a network switch and a plurality of server computers communicatively coupled to the first network switch. The network switch includes a first transceiver configured to transmit data according to a first maximum throughput, and each server computer includes a respective second transceiver configured to transmit data according to a second maximum throughput that is less than the first maximum throughput. The network switch is configured to transmit, using the first transceiver according to the first maximum throughput, first data including a plurality of optical subcarriers to each of the server computers. Each of the server computers is configured to receive, using a respective one of the second transceivers, the first data from the network switch, and extract, from the first data, a respective portion of the first data addressed to the server computer.

An OFDM (orthogonal frequency division multiplexing) transmitter includes an inverse fast Fourier transform circuit, which, in operation, generates, based on digital input data, a complex time-varying digital signal having real and imaginary components; and a multiplexer adapted to generate a time-multiplexed digital signal by time-multiplexing one or more of the real components with one or more of the imaginary components.

An example system includes a first network node, a second network node, and a third network node. The first network node is configured to generate a first optical subcarrier representing first data, and transmit the first optical subcarrier to the second network node. The second network node is configured to receive the first optical subcarrier from the first network node, generate a second optical subcarrier representing the first data, where the second optical subcarrier is different from the first optical subcarrier, and transmit the second optical subcarrier to the third network node.

An example system includes a plurality of network nodes, each including one or more respective first transceivers configured to transmit data according to a first maximum throughput, and one or more respective second transceivers configured to transmit data according to a second maximum throughput that is less than the first maximum throughput. A first network node is configured to transmit, using a respective one of the first transceivers, first data including a plurality of optical subcarriers to two or more second network nodes according to the first maximum throughput, each optical subcarrier being associated with a different one of the two more other network nodes. The two or more second network nodes are configured to receive, using respective ones of the second transceivers, the first data from the first network node.

A method for receiving a modulated receive signal, with a transmission unit having a laser and an electro-absorption modulator. The received optical receive signal is directed towards the laser; due to the irradiance of the optical receive signal onto the laser, the optical frequency of the light radiated from the laser is adapted to and/or aligned with the optical frequency of the received optical receive signal; the light radiated from the laser and the optical receive signal received via the optical waveguide are overlapped in the electro-absorption modulator; the thus-created overlapping signal from the electro-absorption modulator is converted into an electrical receive signal, in particular into an electrical current signal; and a receive signal is provided which corresponds to the electrical receive signal or is derived from same.

An optical IQ modulator with automatic bias control is disclosed. A dither signal is applied to the modulator bias and its signature detected in light tapped from an output of the modulator using a phase sensitive dither detector such as a lock-in amplifier. The detected signal is processed using pre-recorded information defining the direction of the detected signal change relative to a change in the modulator bias, and the bias is adjusted in the direction determined using the information. The IQ phase bias is controlled by dithering I and Q optical signals in quadrature to produce opposite-sign single subband modulation of output light at two different dither frequencies, and detecting an oscillation at a difference frequency using a lock-in detector.

This disclosure describes digitally generating sub-carriers (SCs) to provide isolation and dynamic allocation of bandwidth between uplink and downlink traffic between transceivers that are communicatively coupled via a bidirectional link including one or more segments of optical fiber. Separate uplink and downlink communication channels may be created using digitally generated SCs and using the same transmitter laser. In some implementations, one or more of the nodes include a transceiver having at least one laser and one digital signal processing (DSP) operable for digitally generating at least two SCs and detecting at least two SCs. The transceiver can transmit selected SCs, and can receive other SCs. Accordingly, the transceiver can facilitate bidirectional communication, for example, over a single optical fiber link. In some instances, techniques can facilitate dynamic bandwidth assignment by facilitating adding or blocking of optical subcarriers from transmission in an uplink or downlink direction.

Optical transmitters configured to modulate optical signals with a path-dependent phase modulation scheme. In certain examples, an optical transmitter includes an optical source that emits a carrier waveform, a modulator configured to modulate the carrier waveform according to a path-dependent phase modulation scheme to produce a modulated optical signal, a mapping module configured to map a data payload to the path-dependent phase modulation scheme, each symbol in the path-dependent phase modulation scheme including a concatenation of at least one location bit and a path bit, the at least one location bit identifying an amount of a phase transition in the modulated optical signal and the path bit identifying a direction of the phase transition, and a pulse-shaping filter configured to control the modulator, based on an output from the mapping module, to impose the path-dependent phase modulation scheme on the carrier waveform to generate the modulated optical signal.

An example node includes a receiver, a switch circuit, and a transmitter. The receiver is configured to receive a first modulated optical signal including a first plurality of optical subcarriers, and supply a plurality of data streams based on the first plurality of optical subcarriers. Each of the data streams is associated with a corresponding one of the plurality of optical subcarriers. The switch circuit is configured to receive the data streams, and supply the data streams to a plurality of switch outputs. The transmitter is configured to receive the data streams, and supply a second modulated optical signal based on the data streams. The second modulated optical signal carries a second plurality of optical subcarriers. Each of the second plurality of optical subcarriers is associated with a corresponding one of the data streams.