University of Birmingham > Talks@bham > Theoretical Physics Seminars > Suppression of Polarization Impairments In Fibre Raman Amplifiers

Suppression of Polarization Impairments In Fibre Raman Amplifiers

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  • UserDr Sergey Sergeev, Aston University
  • ClockThursday 25 November 2010, 13:45-15:00
  • HouseTheory Library.

If you have a question about this talk, please contact Dr Dimitri M Gangardt.

Polarization impairments are among major factors limiting the progress in further increase of transmission rates and overall capacity of the next generation of optical networks based on distributed fiber Raman amplification. Application of this technology for ultra-high bit-rate communication systems requires the design of quasi-isotropic media, i.e., addressing the issue of polarization impairments in a form of polarization mode dispersion (PMD) and Raman polarization dependent gain (PDG). PMD leads to pulse broadening caused by varying group velocities for the pulses with different states of polarization (SOPs). PDG is the dependence of Raman gain on the input signal SOP . By the traditional approach, spinning the fiber periodically, it is possible to reduce PMD to below 0.04 ps/km1/2, but this is accompanied with a simultaneous increase in Raman PDG . All the existing PDG mitigation schemes are rather expensive (polarization multiplexing of pump laser diodes, application of a depolarizer) or not very effective (backward pumping) in the case of low PMD fibers. To develop a reliable technique for simultaneous mitigation of both PMD and PDG , we have developed an advanced vector model of a fiber Raman amplifier accounting for the random birefringence and arbitrary spin profile of the fiber. Using this model, it was shown that it is possible to mitigate both PDG and PMD by adopting a fiber with a particular spin profile or, more specifically, a two-section fiber (‘two-section approach’) in which the first section has no spin and the second one is periodically spun.

This talk is part of the Theoretical Physics Seminars series.

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