Abstract: An optical network node for an n-channel dense wavelength division multiplexing (DWDM) optical communications network, includes an add path for adding an n-channel wavelength multiplex onto the network. The add path has an n-channel signal combiner for combining the n signal channels. An optical amplifier amplifies an output of the signal combiner. A multichannel wavelength selective filter with variable-per-channel attenuation filters out noise from the amplifier on a channel which carries no content to be added to the network, and controls amplitude of signals in channels to be added to the network. An add coupler couples the add path to the network.

Abstract: An optical network node for an n-channel dense wavelength division multiplexing (DWDM) optical communications network, includes an add path for adding an n-channel wavelength multiplex onto the network. The add path has an n-channel signal combiner for combining the n signal channels. An optical amplifier amplifies an output of the signal combiner. A multichannel wavelength selective filter with variable-per-channel attenuation filters out noise from the amplifier on a channel which carries no content to be added to the network, and controls amplitude of signals in channels to be added to the network. An add coupler couples the add path to the network.

Abstract: The add path of a dense wavelength division multiplexing (DWDM) add/drop node comprises an n:1 coupler for combining n signal sources. The combined signal is amplified and then demultiplexed. Each output of the demultiplexer is passed through a variable optical attenuator (VOA) and the VOA outputs multiplexed to form the add signal. Channels carrying no add signal and not used to control the added signals are attenuated to zero to remove a broadband noise contribution from those channels. The signal sources are run at maximum power and the signals of those channels are attenuated by the respective VOAs to control their amplitude and optimize the optical signal to noise ratio of the add signal.

Abstract: The invention provides an optical communication system (10) comprising a plurality of mutually interconnected bi-directional optical waveguide rings (20, 30, 40, 50, 60) in which radiation modulated with communication traffic propagates. The radiation is partitioned into 32 distinct wavebands. Interfaces (70, 80, 90, 100, 110, 120) are included in the system (10) where communication traffic propagating in the rings transfers from one ring to another. Each interface (70) is capable of providing an all-optical waveband reconfigurable communication link between the rings (20, 30, 40, 50, 60). At each interface (70), conversion of optical radiation to corresponding electrical signals is not required when transferring communication traffic from one ring to another, thereby providing the system (10) with a potentially larger communication bandwidth compared to conventional optical communication systems.

Abstract: The add path of a dense wavelength division multiplexing (DWDM) add/drop node comprises an n:1 coupler for combining n signal sources. The combined signal is amplified and then demultiplexed. Each output of the demultiplexer is passed through a variable optical attenuator (VOA) and the VOA outputs multiplexed to form the add signal. Channels carrying no add signal and not used to control the added signals are attenuated to zero to remove a broadband noise contribution from those channels. The signal sources are run at maximum power and the signals of those channels are attenuated by the respective VOAs to control their amplitude and optimize the optical signal to noise ratio of the add signal.

Abstract: The invention provides a radiation power equalizer for an optical communication system, the equalizer characterized in that it includes: (a) an optical demultiplexer (300) for partitioning information-bearing radiation received at the equalizer into one or more radiation components corresponding to wavelength division multiplexed communication channels of the system; (b) a liquid crystal cell array (310) for selectively transmitting or attenuating said one or more radiation components; (c) an optical multiplexer (330) for combining one or more of the radiation components transmitted or attenuated through the cell array (310) to provide combined radiation; (d) a transmitter erbium-doped fiber amplifier (70) coupled to a PIN diode detector array (120) for measuring radiation power present in said one or more of the radiation components included in the combined radiation and generating one or more corresponding component radiation power indicative signals; and (e) a control module (130) for receiving said one or

Abstract: The invention provides a radiation power equalizer for an optical communication system, the equalizer characterized in that it includes: (a) an optical demultiplexer (300) for partitioning information-bearing radiation received at the equalizer into one or more radiation components corresponding to wavelength division multiplexed communication channels of the system; (b) a liquid crystal cell array (310) for selectively transmitting or attenuating said one or more radiation components; (c) an optical multiplexer (330) for combining one or more of the radiation components transmitted or attenuated through the cell array (310) to provide combined radiation; (d) a transmitter erbium-doped fiber amplifier (70) coupled to a PIN diode detector array (120) for measuring radiation power present in said one or more of the radiation components included in the combined radiation and generating one or more corresponding component radiation power indicative signals; and (e) a control module (130) for receiving said one or

Abstract: The invention provides an optical communication system (10) comprising a plurality of mutually interconnected bi-directional optical waveguide rings (20, 30, 40, 50, 60) in which radiation modulated with communication traffic propagates. The radiation is partitioned into 32 distinct wavebands. Interfaces (70, 80, 90, 100, 110, 120) are included in the system (10) where communication traffic propagating in the rings transfers from one ring to another. Each interface (70) is capable of providing an all-optical waveband reconfigurable communication link between the rings (20, 30, 40, 50, 60). At each interface (70), conversion of optical radiation to corresponding electrical signals is not required when transferring communication traffic from one ring to another, thereby providing the system (10) with a potentially larger communication bandwidth compared to conventional optical communication systems.