Abstract: An optical network includes an optical ring that is capable of transmitting, between two or more nodes, a plurality of working traffic streams that include traffic transmitted in one of a plurality of wavelengths. A node is capable of transmitting, in a first wavelength, a first protection traffic stream associated with a first working traffic stream, in response to an interruption of the first working traffic stream. A node is also capable of transmitting, in a second wavelength, a second protection traffic stream associated with a second working traffic stream, in response to an interruption of the second working traffic stream. The optical network also includes a regeneration element capable of selectively regenerating the first protection traffic stream. The regeneration element is also capable of tuning the regeneration element to receive traffic in the second wavelength and of selectively regenerating the second protection traffic stream.

Abstract: A method for determining gain for an optical signal includes measuring a first power level that is an output power level of an optical signal at a first optical node, communicating the optical signal to a second optical node, and communicating the first power level to the second optical node in an optical supervisory channel of the optical signal. The method further includes receiving the optical signal at the second optical node, measuring a second power level of the optical signal at the second optical node, and determining a gain for the optical signal based on the first and second power levels.

Abstract: An optical amplification device which includes first and second optical amplifiers, and a controller. The first optical amplifier receives a light and amplifies the received light. The second optical amplifier receives the light amplified by the first optical amplifier, and amplifies the received light. When a level of the light received by the first optical amplifier changes by ?, the controller controls a level of the light received by the second optical amplifier to change by approximately ??. In various embodiments, the controller causes the sum of the gains of the first and second optical amplifiers to be constant. In other embodiments, the optical amplification device includes first and second optical amplifier and a gain adjustor. The gain adjustor detects a deviation in gain of the first optical amplifier from a target gain, and adjusts the gain of the second optical amplifier to compensate for the detected deviation.

Abstract: A method for controlling an amplifier in an optical network includes determining primary pump power information for a primary amplifier and communicating the primary pump power information to a secondary amplifier coupled to the primary amplifier. The method also includes generating secondary pump control information for the secondary amplifier based on the primary pump power information and amplifying a first optical signal at the secondary amplifier based on the secondary pump control information.

Abstract: An optical network includes an access ring, a local ring, one or more add/drop nodes (ADNs), a first gateway and a second gateway. The access ring couples the plurality of gateways and transmits optical signals to and from the gateways, the optical signals comprising multiple wavelengths each wavelength operable to carry traffic. The local ring couples one or more of the ADNs and transmits optical signals to and from the ADNs. Additionally, the ADNs are capable of adding and dropping traffic to and from the local ring in one or more wavelengths. The first gateway is capable of receiving broadcast traffic on the access ring, the broadcast traffic transmitted in one or more wavelengths of the optical signals transmitted on the access ring and forwarding, on the access ring, a first copy of the broadcast traffic received on the access ring.

Abstract: A method for determining gain for an optical signal includes measuring a first power level that is an output power level of an optical signal at a first optical node, communicating the optical signal to a second optical node, and communicating the first power level to the second optical node in an optical supervisory channel of the optical signal. The method further includes receiving the optical signal at the second optical node, measuring a second power level of the optical signal at the second optical node, and determining a gain for the optical signal based on the first and second power levels.

Abstract: A method and system for a data centric architecture in an optical network are provided. In one embodiment, a method and system for a data centric architecture in an optical network includes an optical ring. A number of local nodes are coupled to the optical ring and are configured to receive traffic at a receiving wavelength by optically broadcasting with electrical tag discrimination. Each local node is also configured to transmit traffic at an assigned wavelength different from the transmitting wavelengths assigned to the other local nodes. The transmitting wavelengths are each transmitted at a bandwidth less than the receiving wavelength. A data center node is coupled to the optical ring and operable to receive traffic from the local nodes, sort at least some of the traffic based on the destination of the traffic, and transmit the traffic at the receiving wavelength to the destination.

Abstract: A method for correcting power tilt in an optical signal includes tapping off a representative portion of an optical signal and separating the representative portion into a first signal and a second signal. The first signal includes a first wavelength band and the second signal includes a second wavelength band different from the first wavelength band, wherein each wavelength band includes more than one channel. The method also includes detecting a power level of the first signal, detecting a power level of the second signal, and comparing the power levels of the first and second signals. The method further includes determining a power tilt for the optical signal based on the comparison and adjusting an amplifier gain based on the power tilt.

Abstract: A method and system for controlling the gain of the amplification of an optical signal is provided that includes both electrical feedforward and feedback. In a feedforward portion of an optical amplifier, the method includes receiving an optical signal and measuring an input power. Based on the measured input power and a desired gain, a feedforward pump power is determined. The pump power is adjusted based on the determined pump power. In a feedback portion of an optical amplifier, an output power is measured and gain is determined based on the output power and the measured input power. The measured gain is compared to a desired gain and the pump power is adjusted based on that comparison.

Abstract: A method and a system for setting a tunable filter in an optical network are provided. In one embodiment, a method for setting a tunable filter in an optical network includes rejecting a reference wavelength using a fixed filter from an input optical signal to generate a passthrough optical signal. A tunable filter is adjusted to maintain the tunable filter at the reference wavelength. The tunable filter is adjusted to a selected wavelength based on a determination of the reference wavelength.

Abstract: The invention provides an optical fiber amplifier which assures stable operation of a pump light source and efficiently makes use of residual pump power to achieve improvement in conversion efficiency. The optical fiber amplifier includes a rare earth doped fiber. Pump light from a pump light source is introduced into one end of the rare earth doped fiber by way of a first optical coupler, and residual pump light originating from the pump light and arriving at the other end of the rare earth doped fiber is applied to the other rare earth doped fiber amplifier or the loss compensation of a dispersion compensating fiber by Raman amplification.

Abstract: An optical network includes an optical ring that carries optical traffic in a plurality of wavelengths. The network also includes a number of passive add/drop nodes that are coupled to the optical ring. The passive add/drop nodes each include an optical coupler that is coupled to the optical ring and that receives the optical traffic on the optical ring. The optical coupler both passively drops a copy of the optical traffic and passively forwards a copy of the same optical traffic along the optical ring. The add/drop nodes do not terminate any portion of the optical traffic forwarded by the optical coupler. The network also includes a number of gateway nodes that are each coupled to the optical ring. The gateway nodes selectively pass or terminate each wavelength of the optical traffic. In addition, the network is configured such that the passive add/drop nodes and the gateway nodes are coupled to the optical ring such that none of the passive add/drop nodes are adjacent to one another in the optical ring.

Abstract: The invention provides an optical fiber amplifier which assures stable operation of a pump light source and efficiently makes use of residual pump power to achieve improvement in conversion efficiency. The optical fiber amplifier includes a rare earth doped fiber. Pump light from a pump light source is introduced into one end of the rare earth doped fiber by way of a first optical coupler, and residual pump light originating from the pump light and arriving at the other end of the rare earth doped fiber is applied to the other rare earth doped fiber amplifier or the loss compensation of a dispersion compensating fiber by Raman amplification.

Abstract: An optical amplifier, or optical repeater, for amplifying wavelength division multiplexed (WDM) light. A first demultiplexer demultiplexes the WDM light into first and second lights corresponding to different wavelengths in the WDM light. First and second optical amplifiers amplify the first and second lights, respectively. A first multiplexer multiplexes the amplified first and second lights into a multiplexed light. A dispersion compensator compensates for dispersion in the multiplexed light. A second demultiplexer demultiplexes the dispersion compensated, multiplexed light into the first and second lights. Third and fourth optical amplifiers amplify the demultiplexed first and second lights, respectively. A second multiplexer multiplexes the amplified first and second lights from the third and fourth optical amplifiers into a WDM light. The optical amplifier can be configured so that the first and second lights travel through the dispersion compensator in opposite directions.

Abstract: An optical network includes a first optical ring and a second optical ring. Each optical ring is operable to communicate optical traffic comprising a plurality of sub-bands. The first optical ring comprises a first interconnect node operable to filter traffic in a first sub-band from the first optical ring for communication to the second optical ring. The second optical ring comprises a second interconnect node operable to receive the filtered traffic in the first sub-band from the first interconnect node for communication in the second optical ring.

Abstract: A method for communicating optical traffic in a network comprising a plurality of network nodes includes receiving traffic to be added to the network at a network node. The network is operable to communicate received traffic in an optical signal comprising one or more channels. The method also includes determining a data rate and one or more destination nodes of the received traffic and assigning the received traffic to one or more of the channels of the optical signal based on the determined data rate and the destination nodes. The method further includes configuring one or more of the network nodes to process the traffic contained in the assigned channels based on the data rate and the destination nodes of the optical traffic and communicating the traffic through network in the assigned channels of the optical signal based on the determined data rate and the one or more destination nodes.

Abstract: A system and method for transmitting traffic in an optical network is provided. The system includes an optical ring. A plurality of local nodes are coupled to the optical ring. Each local node of the plurality of local nodes configured to receive traffic at an assigned wavelength, disparate from wavelengths assigned to other local nodes. A data center node is coupled to the optical ring and operable to receive traffic from the plurality of local nodes, sort at least some of the traffic by destination, and transmit the traffic to a corresponding destination node at the assigned wavelength for that node.

Abstract: In one embodiment, a method is provided for an in-service upgrade of a twin ring optical network comprising a plurality of passive add/drop nodes coupled using a first optical fiber ring and a second optical fiber ring. The method includes interrupting optical traffic travelling in a first direction on the first optical fiber ring at a first interruption location between a first passive add/drop node and a second passive add/drop node. The method further includes interrupting optical traffic travelling in a second disparate direction on the second optical fiber ring at a second interruption location between the first add/drop node and the second add/drop node. The network provides protection switching such that interrupting traffic flow at the first or second interruption locations does not prevent traffic on the network from reaching any add/drop node. The method also includes inserting an optical gateway node into the network.

Abstract: An optical cross-connect includes multiple input ports that each receive an optical input signal and multiple output ports that each output an optical output signal. The optical cross-connect also includes a distributing amplifier associated with each input port that generates multiple copies of the input signal received at the associated input port. Furthermore, the optical cross-connect includes multiple filter units that receive a copy of one or more of the input signals from one or more of the distributing amplifiers and forward traffic in selected channels of one or more of the received copies. In addition, the optical cross-connect includes a combining amplifier associated with each output port. Each combining amplifier receives the traffic in one or more of the channels forwarded by one or more of the filter units and combines the received traffic into an output signal to be output from the associated output port.

Abstract: In one embodiment, a method of passively adding traffic from a first optical network to a second optical network includes receiving ingress traffic from an optical ring of the first network at a node coupled to the first network, generating a first and second copy of the traffic, passively forwarding the first and second copies of the traffic, splitting the second copy of the traffic into multiple substantially identical copies, and filtering at least one of the copies of the second copy of the traffic into one or more constituent wavelengths. The method further includes selectively forwarding the signal in one or more constituent wavelengths of the second copy of the traffic to a node coupled to the second network, receiving the forwarded signal in one or more wavelengths at the node, and adding the forwarded signal in one or more wavelengths to an optical ring of the second network.