Abstract: An optical transmitter apparatus comprises at least three input transmitters that each provide at an output an NRZ optical signal, at least two of the NRZ optical signals having substantially the same bit rate, each of the signals having a bit rate which is less than 100 Gbit/s and the sum of the bit rates of all of the at least three transmitters being equal to or greater than 100 Gbit/s, an NRZ to RZ converter associated with each transmitter which converts each NRZ signal into an optical RZ signal, an optical time division multiplexer which converts the RZ signals into at least two further signals, and a polarization multiplexer which processes the two further signals to provide two output signals of differing polarization.

Abstract: An optical transmitter apparatus capable of a transmission rate of at least 100 gbit/second comprises at least three input transmitters that each provide at an output an NRZ optical signal, at least two of the NRZ optical signals having substantially the same bit rate, each of the signals having a bit rate which is less than 100 Gbit/s and the sum of the bit rates of all of the at least three transmitters being at least equal to 100 Gbit/s, an NRZ to RZ converter associated with each transmitter which converts each NRZ signal into an optical RZ signal with the signal remaining in the optical domain during conversion, the optical RZ signal having the same bit rate as the corresponding NRZ signal, an optical time division multiplexer which converts the RZ signals into at least two further signals, one of the further signals being formed by bitwise interleaving the bits of the at least two of the RZ signals which have the same bit rate, and a polarisation multiplexer which processes the two further signals to pr

Abstract: The invention relates to a communications node (10, 90, 100) for routing a plurality of Wavelength Division Multiplexed (WDM) optical signals, the node having a plurality of line units (12) between its inputs and outputs, each line unit including a splitter (14) and a Wavelength Selective Switch (WSS) (16), wherein the splitter (14) is arranged to split an incoming WDM signal into a plurality of WDM signals and to pass them to each WSS in the plurality of line units, each WSS (16) being arranged to selectively route any one or more channels of its received WDM signals to its associated output. Such an arrangement has the advantage of providing a more cost effective realisation of a node with a high nodal degree. The invention provides a technical solution to the problem of connecting a plurality of inputs to a plurality of outputs in a multi-port WDM node. The node has particular application in a mesh network where the nodal degree may be high.