Cisco Technology, Inc.

Mauro Brunella

Stefano Piciaccia

Enrico Griseri

Rosanna Pastorelli

Enrico Self

Gabriele Maria Galimberti

Randy Zhang

Giovanni Osnago

Luca Gumier

A method for optical restoration in an optical network is provided. A network controller obtains, from one or more optical nodes of an optical network, at least one failure notification indicating a failure of a primary path between a first node and a second node. The network controller forwards to a first set of optical nodes, data-plane parameters for optical components of the first set of optical nodes. The first set of optical nodes include the first node, the second node, and one or more intermediate nodes, and forms a restoration path for the primary path. The data-plane parameters for the optical components are forwarded in parallel to the first set of optical nodes of the restoration path so as to activate the restoration path in parallel. The network controller switches traffic from the primary path to the restoration path.

Method and system for optical path restoration

At a first optical node of an optical communications system, during a signal initialization phase, a first optical pattern is received that includes a prefix indicating a beginning of a signal, a first word, and a first working signal for verifying stability of a connection between the first optical node and a second optical node of the optical communications system. A second optical pattern is transmitted that includes the prefix, a second word different from the first word, and the first working signal. A third optical pattern including the prefix, the first word, and a second working signal is received. Based on determining that a duration of the second working signal is greater than a duration of the first working signal plus a predetermined time, the first optical node determines that the second optical node is an adjacent node of the first optical node.

Optical safety and connections discovery

Techniques are presented herein to set power levels for multiple Raman pump wavelengths in a distributed Raman amplification configuration. A first receive power measurement is obtained at a second node with a controlled optical source at a first node turned on and with a plurality of Raman pump lasers at different wavelengths at the second node turned off. A second receive power measurement is obtained at the second node with the controlled optical source at the first node turned on and the plurality of Raman pump lasers turned on to respective reference power levels to inject optical Raman pump power at a corresponding plurality of wavelengths into the optical fiber span. Based on a target Raman gain and a target Raman gain tilt, respective ratios of a total power are obtained, each ratio to be used for a corresponding one of the plurality of Raman pump lasers.

Multi-wavelength distributed raman amplification set-up

An optical fiber carries optical channels injected into the optical fiber to a Raman amplifier. A controller determines a static tilt associated with the channels in the fiber due to wavelength dependent losses. A photodiode measures a total power of the channels at an output of the Raman amplifier. The controller determines a dynamic tilt associated with channels in the fiber based in part on the measured total power. The dynamic tilt is induced by Stimulated Raman Scattering (SRS) in the fiber and varies as a function of a total power of the signals injected into the fiber. The controller determines a total tilt with which to offset the static and dynamic tilts. The controller sets an amplifier gain tilt applied to the channels equal to the total tilt.

Raman-based static and dynamic tilt control in an optical system

Techniques are presented for automatic tuning of operating parameters, e.g., amplifier gain, in an optical network. A section of an optical network comprises a plurality of spans between optical nodes, and each optical node has an amplifier to amplify optical signals for transmission between optical nodes. Physical network layer data is obtained from the optical nodes for use as input to an analytical model. A set of powers defining an optimum working point of the amplifiers is computed based on variations in amplifier noise figure which depend on amplifier gain. A figure of merit representative of network section performance is computed based on linear and non-linear noise at current power levels of the amplifiers. The figure of merit is evaluated. The set of powers is applied to the amplifiers in the network section when evaluation of the figure of merit indicates that network performance improvement can be achieved.

Self-tuning an optical network at an operating point

Techniques, in the form of an apparatus, logic and a method, are provided to set power levels for multiple Raman pump wavelengths in a distributed Raman amplification configuration in order to achieve a target gain and tilt or desired gain profile. A Raman pump light source is activated at each of a plurality of pump wavelengths and at each of a plurality of pump power levels such that only one pump wavelength at a given pump power level is active at a time to thereby amplify an optical probe signal in the optical fiber to produce an amplified probe signal. The level of the amplified probe signal at each of the pump power levels for the plurality of pump wavelengths is measured. The pump power level for each of the plurality of pump wavelengths is computed based on the measured levels of the amplified probe signals due to each of the pump power levels and at each of the pump power levels for the plurality of pump wavelengths.

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Brugherio, Italy

Mauro Brunella