Northern Telecom Limited

Pirelli Cavi E Sistemi S.p.a.

Cisco Photonics Italy S.r.l.

Ross Alexander Saunders

Maurice M O'Sullivan

Alan Robinson

Rongqing Hui

Nigel Baker

Dietmar Garthe

An embodiment includes an optical source, an optical receiver, and an interconnecting optical fiber. A data sequence is received and encoded or formatted as an IP packet using an encoding format capable of returning a signal representing the IP packet to a predetermined value at the beginning of each bit period of the IP packet at a physical layer of the network. The encoded IP packet is then transmitted directly over an optical layer of the network without adapting the IP packet to another encoding format or using an adaptation layer in the network (e.g., at a data link layer or higher). The optical receiver receives the IP packet and then a clock signal is extracted without the overhead and costs associated with additional adaptation or encoding of the IP packet. When the optical source is in an idle state, a mark-hold state (more generally called a filler signal) is formatted with the same encoding format and transmitted to the optical receiver directly over the optical layer in order to maintain a synchronous clock during the idle state.

Method and apparatus for transmitting an internet protocol (IP) packet within a fiber optic network

An embodiment includes a polarization beam splitter and a feedback unit, preferably having an autocorrelator, a processing unit and a polarization controller. Polarized splitter separates the lower-speed tributary signals out of the higher-speed optical signal based upon a polarization relationship (e.g., orthogonal) between the tributary signals. The feedback unit, typically an autocorrelator and a polarization adjustment device, adjusts the higher-speed signal's state of polarization based upon an autocorrelation value of one of the lower-speed tributary signals. The autocorrelation value of one of the lower-speed tributary signals is provided to the polarization adjustment device, which typically includes a processing unit and a polarization controller. The polarization adjustment device adjusts the higher-speed signal's polarization state based upon the autocorrelation extinction ratio value. Ideally, this type of adjustment feedback is performed until the autocorrelation value is maximized for optimal demultiplexing. This type of adjustment is normally performed as part of a feedback loop to track changes in the higher-speed signal's state of polarization.

Method and apparatus for polarization multiplexing and demultiplexing optical tributary signals

An embodiment includes a gating device, a feedback device and a control device. Soliton pulses are received by the gating device, which detects and monitors a dispersive-wave between adjacent soliton pulses using a timing circuit. The timing circuit typically provides a gating signal offset in phase from the soliton pulses in order to trigger the gating device. Triggering the gating device allows the dispersive-wave to be accessed and monitored between adjacent soliton pulses. The feedback device, typically using detectors and processing circuitry, measures the energy of the soliton pulses and the energy of dispersive wave. The feedback determines a ratio of the energy levels as an indication of soliton-pulse transmission performance. The indication is provided to the control device as a feedback signal so that the control device can appropriately adjust characteristics of the soliton pulses and improve or optimize transmission performance.

Method and apparatus for monitoring dispersive-wave energy to indicate and optimize soliton transmission performance

In a WDM transmission system carrying amplitude modulated traffic in which significant cross-phase modulation occurs, each of the individual channels is pre-chirped at the transmitter with replicas, or low-pass filtered replicas of the amplitude modulation applied to each of the other channels. Prechirping of each individual channel with a replica of the amplitude modulation applied to that channel may be added in order additionally to provide compensation for self-phase modulation.

Transmission system with cross-phase modulation compensation

An optical interferometer incorporating a signal strength modulated optical phase delay, such as a Kerr effect element in one of its arms is employed to improve the cross-talk isolation/extinction ratio of an optical switch, amplitude modulator, or amplitude modulated optical transmitter. The Kerr element is constructed so that its intensity dependent optical path length is such as to provide destructive interference at the interferometer output when the light input to the interferometer is low, and constructive interference when the input is high. The place of the Kerr effect element can alternatively be taken by an electro-optic modulator driven with an electrical version of the data modulation appearing on the optical signal.

Growing community of inventors

Fife, United Kingdom

Ross Alexander Saunders