A communication system includes three or more nodes and a multi-core fiber having a plurality of cores and being used in at least a partial segment of the connection between the nodes. One node of the nodes is connected to the multi-core fiber and includes a connector configured to add and drop a signal to and from an allocated core exclusively allocated for communication between the one node and another node of the nodes and/or configured to relay a signal transmitted through another core allocated to communication between the other nodes in multi-core fibers connected to the one node.

A monitoring system includes a monitoring device including an optical transmitter and an optical receiver, an optical repeater, and a first MCF transmission path and a second MCF transmission path, each of the paths includes cores, and connects the monitoring device and the optical repeater with each other via the plurality of cores, the optical transmitter generates an optical pulse, and inputs the optical pulse to a first core included in the cores of the first MCF transmission path, the optical repeater loops-back the optical pulse being received from the first core to a second core included in the cores of the second MCF transmission path, and the optical receiver receives the optical pulse being looped-back, as an optical reception pulse, from the cores of the second MCF transmission path, and calculates a corrected reception level, based on the optical reception pulse.

A communications system includes a maximum ratio combining (MRC) circuit for receiving a plurality of data streams and processing the plurality of input data streams using maximum ration combining to improve signal to noise ratio. A MIMO transmitter transmits the MRC processed plurality of data streams over a plurality of separate communications links from the MIMO transmitter. Each of the plurality of separate communications links from one transmitting antenna of a plurality of transmitting antennas to each of a plurality of receiving antennas at a MIMO receiver. The MIMO transmitter transmits the MRC processed plurality of data streams using a channel matrix of an impulse response of a channel. The channel matrix is created using a pilot signal transmitted on a pilot channel.

A communication system includes three or more nodes and a multi-core fiber having a plurality of cores, the multi-core fiber being used in at least a partial segment of the connection between the nodes is provided. One node of the nodes is connected to the multi-core fiber and includes a connector configured to add and drop a signal to and from an allocated core exclusively allocated from among the cores as a communication path between the one node and another node of the nodes and/or configured to relay a signal transmitted through another core of the cores allocated for communication between other nodes in the multi-core fiber connected to the one node, and a relative positional relationship between a connection position of the allocated core in which a signal is added or dropped in the connector and a connection position of another core in which a signal is relayed in the connector is the same for all of the nodes connected to the multi-core fiber.

A node included in an optical power supply system which includes three or more nodes and a multi-core fiber having a plurality of cores, the plurality of cores being used in at least a partial segment of the connection between the nodes includes: a power supply light dropping unit configured to drop a portion or all of a power supply light from one core of the plurality of cores of the multi-core fiber; a photoelectric conversion unit configured to convert the portion or all of the power supply light dropped by the power supply light dropping unit to an electrical signal; and a power supply target facility configured to operate with the electrical signal converted by the photoelectric conversion unit.

Optical amplifier assembly for spatial division multiplexing (SDM) optical communication systems. Each optical amplifier assembly includes a single pump assembly configured for causing amplification of signals traveling on separate fiber paths in different directions. Each fiber path includes a plurality of spatial dimensions. The single pump assembly includes a plurality of pump sources to provide redundancy and the optical amplifier assembly further includes splitters for splitting outputs of the pump sources to amplifiers coupled to the different spatial dimensions. Different modulation formats may be used on the different spatial dimensions with different pump power being provided to each of the modulation formats. Amplifiers with complementary outputs may be coupled to average out gain deviations.

The invention relates to a mode selection method for a system for MIMO transmission on an optical fiber of multimode type. It comprises a step of measuring the transfer matrix of the transmission channel made up of a set of modes of the optical fiber (110), a step of transforming (120) the transfer matrix into a block diagonal matrix, each block being associated with a mode subset, a step of determining (130) the gain and/or the transmission capacity for each of the mode subsets, and a selection (140) of the mode subset corresponding to the highest gain and/or capacity, the MIMO transmission system then using only the modes of the subset thus selected to transmit on the optical fiber. The invention relates also to a core selection method for a system for MIMO transmission on optical fiber of multicore type.

A method of transmitting communications traffic, the method comprising steps of receiving a sequence of communications traffic bits; and mapping the sequence of communications traffic bits onto a respective one of a plurality of transmission symbols for transmission during a symbol time. Each transmission symbol is identified by a respective first symbol identifier indicative of a respective one or more of a plurality, M, of wavelengths for a transmission signal and a respective second symbol identifier indicative of a respective one or more of a plurality, N, of optical fibres on which to transmit the transmission signal.

An arrayed waveguide grating (AWG) based multi-core and multi-wavelength interconnection network, comprising N upper-level switches, N lower-level switches, and a network intermediate stage, with each upper- and lower-level switches has N CWDM optical transceiving modules. The N optical transceiving modules of each upper-level switch is connected with n m?1 multi-core optical multiplexing modules, the N optical transceiving modules of each lower-level switch is connected with n 1?m multi-core demultiplexing modules, the network intermediate stage is comprised of n.sup.2 r?r multi-core and multi-wavelength wiring modules. The upper-level multi-core optical multiplexing modules, the lower-level multi-core demultiplexing modules, and the n.sup.2 r?r multi-core and multi-wavelength wiring modules of the network intermediate stage are connected via an m-core MPO-MPO optical fiber jumper. The wiring complexity of the interconnection network is O(N.sup.2/r), with employment of a wavelength set of ?={?.sub.0, . . . , ?.sub.k-1}. The present invention conserves wavelength resources of communication windows, enhances scalability of the AWG based interconnection network, while reduces network wiring complexity.

The present invention relates to a method for dual-polarisation SDM transmission over optical fibre. The transmission method uses specific I/Q coding for combating the effects of PDL. The modulation symbols to be transmitted on the 2N polarisation states of the N wavelengths are broken down into real values and imaginary values (220). A first orthogonal linear transformation (230-1) is applied to the vector of the real values thus obtained and a second orthogonal linear transformation (230-2), separate from the first, is applied to the vector of the imaginary values thus obtained. A complex scalar solving an irreducible polynome of [X] in is multiplied with the first or second transformed vector before the two transformed vectors are summed (240) in order to provide a vector of transmission symbols for modulating the different states of polarisation of the spatial elementary channels.