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March, 2002 Wavelength-Dependent Gain of Raman Fiber Optical Amplifiers |
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Fiber Raman amplifiers are becoming increasingly important in optical fiber communication systems since they provide both lower noise performance and a wider wavelength coverage than conventional optical amplifiers.In fiber Raman amplifiers, a strong pump laser provides gain to signals at longer wavelengths through stimulated Raman scattering within the optical transmission fiber. The Raman gain will depend strongly on the wavelength difference between the pump and signal beams and weakly on the absolute pump wavelength. Previous measurements of the Raman gain have focused on its strong dependence on the wavelength difference between the pump and signal beams and have ignored the weaker pump-wavelength dependence. With the growing potential for widespread use of fiber Raman amplifiers in deployed systems, more complete measurements of the Raman gain are needed to provide input for system simulations. In the EEEL Optoelectronics Division, we have recently completed measurements of the dependence of the Raman gain on both the difference between the pump and signal wavelengths and the absolute pump wavelength. The pump-wavelength dependence was measured using two complimentary techniques; a brute-force comparison of the Raman gain at different pump wavelengths and a simpler, more elegant, comparison of the asymmetry in the Stokes and anti-Stokes Raman gain at a fixed pump wavelength.These measurements, made on four standard telecommunication fibers, represent the first direct measurements of the pump-wavelength dependence. Contact:
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