Abstract: The invention relates in general to a method, an apparatus and a unit for operating a Wavelength Division Multiplexing Access Network 25, and in particular to unbundling wavelengths in the network 25. Embodiments of the invention disclose monitoring a plurality of wavelengths of the Wavelength Division Multiplexing Access Network 25 to determine at least one available wavelength that is free for use. The transmitter then automatically transmits data to at least one user device 22 via at least one available wavelength.

Abstract: An optical network terminal (ONT) for use in an optical access network and comprising: an optical transceiver arranged to communicate with an optical line terminal using a wavelength which is modulated to carry sub-channels; a second transceiver arranged to communicate with a number of subscriber equipment using respective subscriber equipment channels; the ONT arranged to automatically map each subscriber equipment channel to a respective sub-channel of the wavelength without using an address associated with the respective subscriber equipment.

Abstract: An optical network includes a first passive optical network optical line terminal that transmits a first optical signal at a first wavelength, coupled to a first port of a first optical filter arrangement, and a second passive optical network optical line terminal that transmits a second optical signal at a second, different wavelength, coupled to a second port of the first optical filter arrangement. An optical coupler, connected between the second terminal and the second port of the first optical filter, couples optical signals at a predetermined set of wavelengths from a third optical line terminal into the second port. A passive optical distribution node connects to optical network terminations and distributes optical signals between the optical line terminals and the optical network terminations. A method of provisioning an optical network is also described.

Abstract: An optical network includes a first passive optical network optical line terminal, coupled to a first port of a first optical filter arrangement, and a second passive optical network optical line terminal, coupled to a second port of the first optical filter arrangement. An optical coupler is connected between the second passive optical network line terminal and the second port of the first optical filter arrangement. A passive optical distribution node is coupled to a third port of the first optical filter arrangement.

Abstract: An optical PON network comprises a central office which generates N DPSK modulated optical signals, where N is an integer greater than 1, an optical coupling which connects the N signals to at least one optical fiber, a passive distribution node located remotely from the central office which has at least one input port that is coupled to the fiber and a plurality of output ports, the node being arranged to transmit a first wavelength of the N signals to at least one of its output ports, and at least one optical network unit connected through a respective optical fiber to the first output port of the passive distribution node. The passive distribution node comprises an arrayed waveguide grating which provides a passive optical connection between its input port and the first output port and which for that connection functions as a bandpass filter having a profile and bandwidth selected such that the DPSK optical signal passed to the input node is converted to an intensity modulated signal at the output port.

Abstract: The invention relates in general to a method, an apparatus and a unit for operating a Wavelength Division Multiplexing Access Network 25, and in particular to unbundling wavelengths in the network 25. Embodiments of the invention disclose monitoring a plurality of wavelengths of the Wavelength Division Multiplexing Access Network 25 to determine at least one available wavelength that is free for use. The transmitter then automatically transmits data to at least one user device 22 via at least one available wavelength.

Abstract: The invention relates to improvements in or relating to multicarrier communication and includes a method and a system for communication between an optical line terminal and a plurality of users over a single optical fibre. A portion of a down-stream optical signal is input to an optical circuit, the downstream signal comprising a plurality of subcarriers modulated at a first frequency, the portion of the downstream optical signal is processed at the optical circuit to remove the plurality of subcarriers and to change the first frequency into a second frequency. The processed portion of the downstream signal is then used for communication in the upstream direction.

Abstract: An optical network terminal (ONT) for use in an optical access network and comprising: an optical transceiver arranged to communicate with an optical line terminal using a wavelength which is modulated to carry sub-channels; a second transceiver arranged to communicate with a number of subscriber equipment using respective subscriber equipment channels; the ONT arranged to automatically map each subscriber equipment channel to a respective sub-channel of the wavelength without using an address associated with the respective subscriber equipment.

Abstract: The invention relates to improvements in or relating to optical networks. Methods and apparatus are disclosed for providing communications services to at least one user. Transmission of an optical signal in the downstream direction is described comprising at least one Wavelength Division Multiplexing channel such that at least one of the channels is an unmodulated channel. The unmodulated channel is arranged to transmit user data from the at least one user in the upstream direction.

Abstract: An optical PON network comprises a central office which generates N DPSK modulated optical signals, where N is an integer greater than 1, an optical coupling which connects the N signals to at least one optical fibre, a passive distribution mode located remotely from the central office which has at least one input port that is coupled to the fibre and a plurality of output node being arranged to transmit a first wavelength of the N signals to at least one of its output ports, and at least one optical network unit connected through a respective optical fibre to the first output port of the passive distribution node. The passive distribution node comprises an arrayed waveguide grating which provides a passive optical connection between its input port and the first output port and which for that connection functions as a bandpass filter having a profile and bandwidth selected such that the DPSK optical signal passed to the input node is converted to an intensity modulated signal at the output port.

Abstract: A ringed optical transmission system comprises along the ring rare earth doped fiber amplifiers. The system has a gain peak with a ?ASE wavelength outside the ?1-?n band of the channels transmitted along the ring, the wavelength corresponding to an ASE emission peak of the amplifiers in the ring. In this manner a lasing peak forming a gain stabilization signal is produced.

Abstract: The invention relates to telecommunications network (10), and in particular to a Passive Optical Network (PON), and a method for operation thereof. The telecommunications network (10, 60) is capable of handling increases in bandwidth per user over the predicted lifetime of the network infrastructure. The telecommunications network (10, 60) further utilises a greater proportion of the potential bandwidth carrying capacity of the network and minimises maintenance requirements. The network (10, 60) is readily adaptable to future bandwidth requirements because redundant optic fibres (18, 27) are provided for making more connections as required. The cost of laying redundant optic fibres (18, 27) is minimal when compared to the cost of laying additional optic fibres at a later date. Furthermore the cost of maintaining the network is kept to a minimum because of the use of PON technology and consequently the overall cost of installing and maintaining the network over a predicted lifetime of 20 years is reduced.

Abstract: In an optical data transmission system, high frequency pulsed optical signals are transmitted along an optical fiber. These pulses are attenuated and distorted by transmission over long optical fibers making detection of data difficult at the receiving end. The allowable pulse profile is determined by an eye diagram which is non-symmetrical with respect to logic 1 and 0 levels. By positioning the eye diagram closer to the logic 0 level, detection in the presence of noise introduced during transmission of the optical pulses, can be significantly improved.

Abstract: A ringed optical transmission system comprises along the ring rare earth doped fiber amplifiers. The system has a gain peak with a ?ASE wavelength outside the ?1-?n band of the channels transmitted along the ring, the wavelength corresponding to an ASE emission peak of the amplifiers in the ring. In this manner a lasing peak forming a gain stabilization signal is produced.

Abstract: In an optical data transmission system, high frequency pulsed optical signals are transmitted along an optical fibre. These pulses are attenuated and distorted by transmission over long optical fibres, making detection of data difficult at the receiving end. The allowable pulse profile is determined by an eye diagram, and the invention uses an eye diagram which is non-symmetrical with respect to logic 1 and 0 levels. By positioning the eye diagram closer to the logic 0 level, detection in the presence of noise introduced during transmission of the optical pulses, can be significantly improved.