Use of Raman amplification effect in advanced fiber optic communication systems

Fiber Raman amplifiers and dispersion management fibers (DMFs) used in high-bit-rate DWDM systems are modeled. Fiber parameters are numerically optimized for next generation fiber-optic systems, and the performances of some commercially available fibers are confirmed. At higher bit rate, group velocity dispersion (GVD) effect broadens optical pulses more quickly and residual dispersion tolerance becomes more sensitive to dispersion profiles. Careful dispersion management is critical in improving system capacity. Raman amplification provides advantages such as broad bandwidth, low noise figure and high optical signal-to-noise ratio (OSNR), etc. Although Raman amplification is far from flat, relatively flat dense wavelength-division multiplexing (DWDM) spectrum can be achieved by using multiple pumps for which the power and wavelength of each pump is carefully tuned. Simulations are done and the comparisons between EDFAs (Erbium-doped fiber amplifiers) and Raman amplifiers demonstrate advantages of the latter.