Abstract: A hub structure for use in an optical network, the optical network comprising a ring structure carrying a bidirectional optical data signal and a plurality of hub structures arranged in-line within the ring structure, the optical data signal comprising primary and secondary path transmission signals having opposing transmission directions on the ring structure, the hub structure comprising a drop unit arranged, in a normal state, to drop and through-connect a primary receive path signal for further processing at the hub structure, and, in a protection state, to drop and through-connect a secondary receive path signal for further processing at the hub structure.

Abstract: A rack structure for a network node system, the rack structure comprising a first rack portion arranged, in use, to receive a plurality of circuit cards in slots and having a plurality of first connector elements disposed on a backplane thereof, each first connector element being arranged to make contact with a corresponding second connector element of one of the cards when it is inserted into one of the slots, and a patch panel rack portion comprising, on a frontplane thereof, a plurality of third connector elements, each third connector element being internally connected to one of the first connectors, whereby the patch panel enables, in use, rewiring of the rack structure from the front of the rack structure.

Abstract: A network hub structure for connecting network elements of a first WDM network supporting a first bit rate WDM data stream to other network elements on a second optical network supporting a second bit rate data stream which is substantially a multiple n of the first bit rate; the hub structure comprising a multiplexing system comprising a plurality of multiplexing units, each multiplexing unit being arranged to multiplex n first WDM data streams into one second data stream, and a switching unit arranged, in use, to selectively cross connect any n first WDM data streams originating from one or more of the network elements of the WDM network destined for any same one of said other network elements to one of the multiplexing units for multiplexing into one said second data stream.

Abstract: A DWDM network supporting first bit rate data streams, the DWDM network comprising a plurality of network hubs interfacing to subscriber line connections, and a core hub for providing cross connections between the network hubs, wherein each of the network hubs comprises a first bi-directional multiplexing unit arranged to multiplex n subscriber data streams each having a second bit rate which is substantially 1/nth of the first bit rate into a single first bit rate data stream for distribution on the DWDM network, and wherein the core hub comprises a plurality of second bi-directional multiplexing units each for de-multiplexing one of the single first bit rate data streams originating from the network hubs into the subscriber data streams and a switching unit arranged to selectively cross-connect the individual subscriber data streams back to individual ones of the second multiplexing units for distribution of the subscriber data streams to their respective destination network hubs in single first bit rate da

Abstract: An optical fibre comprising at least one single core structure arranged in a manner such that, in use, it supports both single-mode and multi-mode propagation for data transfer.

Abstract: An optical modulation system for independently modulating multiple wavelengths and transmitting them along a single output waveguide, the system comprising: a series of optical modulator elements each having at least one modulator waveguide input for inputting a single wavelength and modulation means for modulating the input single wavelength to produce a modulated wavelength output; an array of optical laser emitters, each emitting at a separate wavelength, the array having a series of wavelength outputs, one each of which is interconnected to the waveguide modulator input of the series of optical modulator elements; and an optical multiplexer taking a series of a modulated wavelength outputs having differing wavelengths and for multiplexing the multiple wavelengths together for output onto the single output waveguide.

Abstract: An optical ring network comprising; a plurality of network elements including a core network element interfacing the ring network with an external core network, and at least one ring network element; wherein the core network element includes a first CWDM unit, a first DWDM unit and switching means arranged to cross connect any wavelength channel within or between wavelength bands on the ring network or between the ring network and the core network, and wherein the ring network elements each include, a second CWDM unit and a second DWDM unit, the second CWDM unit being arranged to add/drop at least a first wavelength band at said ring network element from and to the second DWDM unit and to express other wavelength bands onto the next network element

Abstract: An optical ring network structure comprising two or more network elements, and a single optical fiber connection between each pair of neighboring network elements for carrying an optical signal, wherein the ring network structure is arranged in a manner such that, in use, band allocation utilizing multiplexing on each single fiber connection is chosen in a manner such that groups of wavelengths for bi-directional data transfer and for bi-directional redundant data transfer for protection respectively are provided on each single fiber connection.

Abstract: An optical switch comprising at least a first demultiplexer for demultiplexing a series of wavelength division multiplexed signals into corresponding spatially separated demultiplexed signals; a series of first optical to electronic interface units interconnected to said spatially separated demultiplexed signals; an electronic switch for transmitting said data stream to one of a series of output ports under the control of an external control signal; a series of second electronic to optical interface units at said output ports and at least a first multiplexer interconnected to a plurality of optical interface units for multiplexing the optical stream of each interface unit together to form a combined optical data stream output.

Abstract: An optical network element comprising a plurality of subscriber line connections, a WDM unit having a plurality of WDM channel connections, a plurality of subscriber line interface cards and a plurality of trunk line interface cards for optical interfacing between the subscriber line connections and the WDM channel connections, and a switch arranged, in use, in a manner such as to be capable of switching transmission directions between the WDM channel connections and individual ones of the subscriber line connections by suitable switching of an optical path configuration between transmitter ports and receiver ports of the subscriber line interface cards and the WDM channel connections.