Raman amplifier system, apparatus and method for identifying, obtaining and maintaining an arbitrary Raman amplification performance

A Raman amplifier for amplifying a WDM optical signal in an optical fiber propagating therethrough, comprising:

• a pumping device including a plurality of pump lasers configured to produce light centered at different wavelengths so as to produce WDM pump light that is applied to the optical fiber;
• an optical coupler configured to optically interconnect the pumping device with the optical fiber;
• and
• a controller having
• a memory interface retrieve from memory computer-readable instructions and data, said data being arranged in a plurality of sets of drive conditions for said plurality of pump lasers, each of said sets of drive conditions corresponding to a different target profile, each different target profile including multiple wavelength samples distributed across an amplification bandwidth, and
• a processor having an interface configured to communicate with external devices, said processor configured to execute said computer-readable instructions and implement a target setting mechanism and a parameter application mechanism, wherein
• said target setting mechanism is configured to identify a target profile and corresponding operating parameters for the plurality of pump lasers to achieve the target profile, said operating parameters including a set of said plurality of sets of drive conditions, said target profile relating to an operational condition provided to said processor from at least one of said external devices, said target profile having multiple samples and being at least one of
• a predetermined amplification profile having the multiple samples specified across the amplification bandwidth, said amplification bandwidth being a contiguous bandwidth at least as large as a signal bandwidth of a WDM optical signal that is amplified by said Raman amplifier while propagating through an optical fiber, and an output signal level profile having the multiple samples specified across said amplification bandwidth,
• said parameter application mechanism is configured to output at least one control signal that defines said operating parameters so as to adjust an amount of light introduced into said optical fiber from said plurality of pump lasers, and
• said target setting mechanism is configured to compare the multiple samples of said target profile with corresponding samples obtained by monitoring an actual profile so as to determine whether each sub-band of a plurality of sub-bands of said actual profile is within a predetermined tolerance of said target profile across said amplification bandwidth so that said controller can make an adjustment to any of the plurality sub-bands of said actual profile that is not within said predetermined tolerance.

A method for controlling an amplification profile of a Raman amplifier having a plurality of pump lasers that produce light centered at different wavelengths so as to provide WDM pump light, comprising steps of:

• identifying operating parameters for the plurality of pump lasers that correspond with a target profile for said Raman amplifier, said target profile including multiple wavelength samples distributed across an amplification bandwidth and being at least one of
• a predetermined amplification profile having the multiple samples specified across the amplification bandwidth, said amplification bandwidth being a contiguous bandwidth at least as large as a signal bandwidth of a WDM optical signal that is amplified when propagating through an optical fiber, and
• an output signal level profile having the multiple samples specified across said amplification bandwidth;
• comparing the multiple samples of said target profile with corresponding samples obtained by monitoring an actual profile so as to determine whether each sub-band of a plurality of sub-bands of said actual profile is within a predetermined tolerance of said target profile across said amplification bandwidth;
• forming a control signal in a processor derived from said operating parameters, said forming step including retrieving from memory a set of drive conditions for said plurality of pump lasers, said set being one of a plurality of sets of drive conditions that correspond to different target profiles;
• sending said control signal to an optical output adjustment mechanism coupled to said plurality of pump laser;
• and
• adjusting an amount of light introduced into said optical fiber from said plurality of pump lasers to achieve the actual profile that is within the predetermined tolerance of said target profile for any of the plurality sub-bands of said actual profile that is not within said predetermined tolerance.

An apparatus for controlling an amplification profile of a Raman amplifier having a plurality of pump lasers that produce light centered at different wavelengths so as to provide WDM pump light, comprising:

• means for identifying operating parameters for the plurality of pump lasers that correspond with a target profile for said Raman amplifier, said target profile including multiple wavelength samples distributed across an amplification bandwidth and being at least one of
• a predetermined amplification profile having the multiple samples specified across the amplification bandwidth, said amplification bandwidth being a contiguous bandwidth at least as large as a signal bandwidth of an WDM optical signal that is amplified by said Raman amplifier while propagating through an optical fiber, and
• an output signal level profile having the multiple samples specified across said amplification bandwidth;
• means for comparing the multiple samples of said target profile with corresponding samples obtained by monitoring an actual profile so as to determine whether each sub-band of a plurality of sub-bands of said actual profile is within a predetermined tolerance of said target profile across said amplification bandwidth;
• means for forming a control signal derived from said operating parameters that include a set of drive conditions saved in memory that correspond with the target profile, said memory containing other sets of drive conditions that correspond with other target profiles;
• means for sending said control signal to said plurality of pump lasers;
• and
• means for adjusting an amount of light introduced into said optical fiber from said plurality of pump lasers to achieve the actual profile that is within the predetermined tolerance of said target profile for any of the plurality sub-bands of said actual profile that is not within said predetermined tolerance.

An optical communication system comprising:

• a controller having
• a processor,
• a memory having sets of drive conditions that correspond with different target profiles, and
• an interface to a data communications network;
• a first Raman amplifier configured to optically amplify a WDM optical signal while propagating through an optical fiber, wherein a wavelength span of said WDM signal falls within a contiguous amplification bandwidth of said first Raman amplifier;
• the optical fiber;
• and
• a second Raman amplifier configured to receive and Raman amplify said WDM optical signal provided from said first Raman amplifier, said second Raman amplifier having a communications interface that connects to said data communications network, wherein
• said controller is configured to retrieve a predetermined set of drive conditions for laser pumps in said second Raman amplifier and send a control message to said second Raman amplifier with said predetermined set of drive conditions that instructs said second Raman amplifier to adjust a target profile thereof, said target profile including multiple wavelength samples distributed across portions of said contiguous amplification bandwidth,
• said second Raman amplifier being configured to compare the multiple wavelength samples of said target profile with corresponding samples obtained by monitoring an actual profile so as to determine whether each sub-band of a plurality of sub-bands of said actual profile is within a predetermined tolerance of said target profile across said contiguous amplification bandwidth, and
• said second Raman amplifier being configured to adjust an optical output of at least a subset of a plurality of pump lasers therein that provide light centered at different wavelengths so as to produce WDM pump light that causes said actual profile to be within said predetermined tolerance across the amplification bandwidth for any of the plurality sub-bands of said actual profile that is not within said predetermined tolerance.

A computer program product for controlling an amplification profile of a Raman amplifier that includes a plurality of pump lasers that produce light at different wavelengths so as to provide WDM pump light, comprising:

• means for identifying operating parameters for the plurality of pump lasers that correspond with a target profile for said Raman amplifier, said operating parameters including a set of drive conditions for said plurality of pump lasers that correspond with said target profile, said set of drive conditions being one of a plurality of sets of drive conditions that correspond with other target profiles, said target profile including multiple wavelength samples distributed across an amplification bandwidth and being at least one of
• a predetermined amplification profile having the multiple samples specified across the amplification bandwidth, said amplification bandwidth being a contiguous bandwidth at least as large as a signal bandwidth of a WDM optical signal that is to be Raman amplified while propagating through an optical fiber, and
• an output signal level profile having the multiple samples specified across said amplification bandwidth;
• and
• a comparison mechanism configured to compare the multiple samples of said target profile with corresponding samples obtained by monitoring an actual profile so as to determine whether each sub-band of a plurality of sub-bands of said actual profile is within a predetermined tolerance of said target profile across said amplification bandwidth;
• a control signal formation mechanism that derives a control signal from said operating parameters that includes said set of drive conditions and provides said control said to means for sending said control signal to means for adjusting an amount of light introduced into said optical fiber from said plurality of pump lasers to achieve the actual profile that is within the predetermined tolerance of said target profile for any of the plurality sub-bands of said actual profile that is not within said predetermined tolerance.