Cisco Technology, Inc.

Enrico Griseri

Mauro Brunella

Fabrizio Forghieri

Enrico Self

Stefano Piciaccia

Rosanna Pastorelli

Giovanni Osnago

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, 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.

Fiber-adaptive distributed Raman amplifier pump setup scheme

Raman amplifiers with improved signal to noise ratio and four-wave mixing product suppression are provided. In one embodiment, both co-propagating and counter-propagating pump energy are employed to cause Raman amplification effects within a fiber. Improved Raman amplification performance including improved four-wave mixing product suppression facilitates longer distance transmission without regeneration of optical signals and/or denser WDM channel spacings.

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Milan, Italy

Enrico Griseri