Summary form only given. Recent progress in the development of high power lasers of near and mid IR renewed the interest in Raman amplifiers for WDM communication systems. Such amplifiers, demonstrating a number of advantages, may effectively complement currently used networking systems of different scales and applications. The variety of wavelengths of pump lasers available for Raman applications allow us to design broadband Raman amplifiers with a desired gain profile to meet certain requirements for particular networking systems. Reduced nonlinear interactions in a fiber link with a distributed gain, as well as improved noise properties make Raman amplifiers especially attractive for high speed DWDM communications. In this paper we report measured dependence of polarization properties of Raman gain for both co-propagating and counter-propagating pumping schemes with several different types of optical fibers. Experimental data show very low, if any, polarization dependence for backward pumping. On the other hand, the forward pumping for Raman amplifiers with different types and lengths of fibers demonstrate different polarization dependences for each particular case. More careful consideration may relate such a behavior with polarization mode dispersion (PMD) of fibers, which has an essentially statistical origination.
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