Novel fiber design for flat gain Raman amplification using single pump and dispersion compensation in S band

This paper reports on a novel fiber design that has an inherently flattened effective Raman gain spectrum. Simulations show that gain-flattened broad-band Raman amplification, using a single pump, can be achieved in any wavelength band by suitably choosing the fiber parameters and the pump wavelength. The fiber also has a high negative dispersion coefficient-(380-515) ps/km·nm over the operating range of wavelengths-and the shape of the dispersion curve is such that the total link dispersion can be not only compensated but also flattened. Hence, the designed fiber can serve as a lossless, broad-band, dispersion-flattening, and dispersion-compensating module for the S band, wherein lossless operation is achieved using inherently gain-flattened single-pump Raman amplification. The performance characteristics of such a module was modeled taking into account wavelength-dependent splice loss as well as background loss, and it has been shown through simulations that lossless operation with ±0.2-dB gain ripple is achievable over (1480-1511) nm using a single pump. Moreover, dispersion compensation for five spans of transmission in a 10-Gb/s system, over this 32-nm bandwidth in the S band, should be attainable using the proposed design.