Abstract: In a wavelength division multiplex (WDM) optical communications network having a plurality of nodes, each of which comprises a wavelength selective optical cross-connect having a plurality of switching matrices, each switching matrix being provided for switching wavelength channels of a specific wavelength, a method of transmitting information from a start node to a target node includes the steps of applying to respective inputs of switching matrices of the start cross-connect, at least two wavelength channels (working an protection channels) having different wavelengths but which are modulated with the same information; transmitting the working and protection channels to the target cross-connect; and dropping the working and protection channels at outputs of different switching matrices provided for different wavelengths of the target cross-connect.

Abstract: A WDM optical cross-connect has input and output channels for through traffic. A first group of matrices connects the input channels to the output channels. Each input channel is connected to an input of a matrix of the first group and each output channel is connected to an output of the matrix. Input/output channels are provided for adding/dropping traffic. Each add/drop channel is connected to an input/output of a second group of matrices. The outputs/inputs of the second group of matrices are connected to inputs of a third group of matrices or outputs of a fourth group of matrices and the outputs/inputs of the third/fourth group of matrices are connected to inputs/outputs of the first group of matrices such that the matrices of the second, third and first groups of the first, fourth and second groups each form a Clos network.

Abstract: In a wavelength division multiplex (WDM) optical communications network having a plurality of nodes, each of which comprises a wavelength selective optical cross-connect having a plurality of switching matrices, each switching matrix being provided for switching wavelength channels of a specific wavelength, a method of transmitting information from a start node to a target node includes the steps of applying to respective inputs of switching matrices of the start cross-connect, at least two wavelength channels (working an protection channels) having different wavelengths but which are modulated with the same information; transmitting the working and protection channels to the target cross-connect; and dropping the working and protection channels at outputs of different switching matrices provided for different wavelengths of the target cross-connect.

Abstract: An optical switching station comprises a first plurality of input channels for through data traffic, a second plurality of output channels for through data traffic, at least one first optical switching matrix comprising a first group of input connectors connected to the input channels on the switching station and a first group of output connectors connected to the output channels on the switching station, for connecting the input channels and the output channels to each other, and a group of one or more signal shaping units, each of a second group of output connectors being connected with an input of a signal shaping unit belonging to the group and each of a second group of input connectors being connected with an output from one of the signal shaping units.

Abstract: A wavelength division multiplex (WDM) optical cross-connect (OXC) has a plurality (N×M) of input and output channels (iI to iM; o1 to oM) for through traffic. A first group of optical switching matrices (SI-I to SI-N) is provided for connecting the through traffic input channels (iI to iM) to the output channels (o1 to oM), wherein each through traffic input channel (iI to iM) is connected to an input of a switching matrix (SI-I to SI-N) of the first group and each through traffic (o1 to oM) is connected to an output of the switching matrix (S1-1 to S1 -N). Additionally a plurality (P) of input channels (a1 to aP) and/or output channels (o1 to oP) is provided for adding/dropping traffic. Each add/drop input/output channel (a1 to aP, o1 to oP) is connected to an input/output of a second group of switching matrices (S2?-1 to S2?-AD).

Abstract: In the present invention, fast dynamic dispersion compensation on a per-packet basis is performed by using a header recognition scheme at each node in an optical network to extract from each packet the path and bit-rate information. A decision can then be taken on whether dispersion compensation is needed for that packet, and if so, what would be a suitable amount of such compensation.

Abstract: In a method of transmitting data over an optical transmission network, the data to be transmitted is divided into a plurality of data streams, each of which comprises data packets of predetermined lengths with the packet lengths of each stream differing from those of the other streams. Individual packet streams are associated on to respective wavelengths of a wavelength division multiplexed optical signal for transmission over the network.

Abstract: An optical tunable filter/wavelength converter comprises an input for multiple wavelength traffic carrying signals &lgr;1-&lgr;m, an output for converted wavelength carrying signals (&lgr;1′-&lgr;m′), means (20) for routing each of the traffic carrying signals through a demultiplexer to an individual semiconductor optical amplifier (SOA) (22) or to an interferometer arrangement. A laser source (26) provides a further input wavelength to the SOAs, or to the interferometer arrangements, to enable cross-gain or cross-phase modulation from the input signal which thereby provides the converted signal. Means is provided for selectively routing the converted signal to the output.

Abstract: An optical routing device for wavelength division multiplexed (WDM) optical signals includes an optical switch matrix (50) having a first optical switch array (54) and a second optical switch array (52), the first optical switch array being adapted to couple optical signals to the second optical switch array on the basis of the wavelength of respective optical signals. The second optical switch array (52) includes a number of optical switch devices, each of which is dedicated to route traffic on a respective wavelength. The device includes a drop traffic path and a through traffic path, in which the drop traffic path includes a transponder unit (170; 220) that is selectively reconfigurable to couple signals to a through traffic path and thereby provide a signal regeneration path. The transponder unit (170; 220) may be tunable so as to provide a wavelength translation function for any optical signal received by the transponder unit. This feature enables efficient sharing of transponders.