A method for low-rate signal transmission on Optical Transport Networks is provided. In the method, a signal is mapped to a low-rate OPU of a low-rate ODU, wherein the low-rate ODU comprises an ODU overhead section and the low-rate OPU, the low-rate OPU comprises an OPU overhead section and an OPU payload section, the low-rate ODU has a bit rate of 1, 244, 160 Kbps±20 ppm, and the OPU payload section has a bit rate of 1, 238, 954.31 Kbps±20 ppm; OPU overhead bytes and ODU overhead bytes are added to corresponding overhead section; then, the low-rate ODU is multiplexed to an Optical channel Data Unit-k (ODUk) that has a bit rate higher than the bit rate of the low-rate ODU; finally, the ODUk is transmitted via the OTN.

In order to readily carry out communication between terminal stations, a submarine optical communication system includes a first terminal station including a first monitoring means for monitoring the signal quality of dummy light a first dummy light source that outputs dummy light to the second terminal station, and a first light transmitting means for transmitting an optical signal to the second terminal station, the optical signal including a first signal quality of the dummy light; and the second terminal station including a second dummy light source that outputs dummy light to the first monitoring means, a second monitoring means for monitoring the signal quality of the dummy light, and a light receiving means for receiving the optical signal.

Systems, methods, and computer-readable media are described for performing link training to enable optical pass-through (OPT) capabilities of a network node. OPT capabilities may refer to on-chip wavelength routing for a multi-wavelength data input, whereby an intermediate node detects wavelengths that are intended for OPT and transparently passes the wavelengths through to downstream nodes. When executed at an intermediate network node, an OPT link training algorithm can result in the creation of one or more wavelength routing maps that associate wavelengths received on particular inputs to the node with particular outputs of the node. An intermediate node may generate a respective wavelength routing map for each transmit node from which it receives input data. The wavelength routing maps may together implement OPT capabilities at the intermediate node as each wavelength routing map may indicate the manner in which wavelengths are passed through the intermediate node for a given transmit node.

There is provided a method, apparatus and system for determining multipath interference (MPI) in optical communications. It is object of embodiments of the present disclosure to provide an effective, low-cost way of detecting or measuring MPI. To effectively detect and measure the MPI, multiple zero-power gaps are inserted into the transmission signal (optical signal) in time domain. In some embodiments, at least some of the zero-power gaps inserted in the main signal do not overlap the zero-power gaps of the reflection of the main signal. Using the zero-power gaps contained the main signal and the reflection (where applicable), power inside and outside the zero-power gaps are determined. Then, the strength of the MPI is determined based on the determined power inside and outside the zero-power gaps.

An optical system (100) is described including: a reconfigurable optical device (103) with multiplexing wavelength division, comprising a plurality of actuators (A1-AN) and having associated a number of optical channels (M) and a number of degrees of freedom (N) lower than the number of optical channels; an optical stimulus source (106) connected to said reconfigurable optical device (103) to provide an optical stimulation signal (S.sub.in) having a wavelength band including a plurality of wavelengths associated with the optical channels; an optical-electric conversion device (200) configured to receive from said reconfigurable optical device (103) an optical monitoring signal (S.sub.out) corresponding to the optical stimulation signal (S.sub.in) and to provide a group of electrical signals of intensity (S.sub.EL1-S.sub.ELK) each representative of an intensity of the optical monitoring signal (S.sub.out) evaluated at a relative wavelength included in said band. The system also includes a control device (110) configured to control the plurality of actuators (A1-AN) according to said group of electrical signals (S.sub.EL1-S.sub.ELK) and according to a control law.

A method to select a number of fibers for ROADM-equipped nodes of an optical network by which a controller is operative to determine which links are utilized as well as their usage frequencies and then partition a scale of usage frequencies into a number of intervals. By assigning a number of fibers to each one of the intervals, a number of fibers is assigned to each link, according to their usage frequencies, setting the degree for ROADMs at the nodes. Simulations can evaluate the network's performance in terms of a blocking rate representing an overall signal blocking rate by the ROADMs at network nodes. The number of intervals, their ranges, and the number of fibers associated with each interval can be iterated until an improved or satisfactory network performance is achieved.

A receiving device includes a light source, a wave multiplexer, a converter, a demodulator and a processor. The light source outputs local light. The wave multiplexer causes the local light to interfere with a received signal to acquire an optical signal. The converter converts the optical signal into an electrical signal. The demodulator demodulates the electrical signal to acquire a demodulated signal. The processor is configured to correct an error of the demodulated signal. The processor is configured to acquire a signal correction amount and/or an error rate. The processor is configured to control the light source in order to adjust an output intensity of the local light based on the signal correction amount and/or the error rate.

Adaptive bundling of capacity changes in an optical section includes, responsive to a request for a capacity change for a plurality of channels on an optical section, determining spectral loading of the optical section; determining a bundling of changes for the capacity change based on the spectral loading of the optical section; and performing the capacity change based on the bundling. The bundling includes a number of steps to achieve all of the capacity change and a maximum allowable amount of optical spectrum that can be changed in each step. The maximum allowable amount of optical spectrum that can be changed in each step can be adaptively determined based on the channel loading.

This disclosure relates to wavelength division multiplexed (WDM) passive optical networks (PON), and the transmission of point-to-point and broadcast or multicast channels from an optical line transmitter (OLT) to an optical network unit (ONU). There is provided a WDM PON (100) comprising: an OLT (105) coupled to a plurality of ONU (110a, 110b) using an optical fiber network (160); the OLT (105) having one or more WDM transceivers (115a, 115b) each arranged to receive multi-cast and point-to-point channels and wherein the or each WDM transceiver (115a, 115b) is arranged to transmit a said channel to a respective said ONU (110a, 110b) using a respective dedicated wavelength (λa, λb); an input channel switch (130a, 130b) associated with the or each WDM transceiver (115a, 115b) and arranged to selectively couple the input of the WDM transceiver to the multi-cast channels and the point-to-point channels (140,135); wherein the selected multi-cast or point-to-point channels are directly converted to the respective dedicated wavelength.

The present document discloses a method and a system for restoring an optical layer service. The method includes: determining wavelength resource occupancy information of an inner-link of the node and an optical layer link where the node is located; herein the wavelength resource occupancy information includes resource occupancy state information of a wavelength resource corresponding to a Hold Priority; and flooding the wavelength resource occupancy information in a network where the node is located.