Carrier-to-Noise Ratio for Distributed Raman Amplifiers with Different Pumping Configurations

Distributed Raman amplifiers (DRAs) achieve higher bit rate, low noise figure, a decreased nonlinear penalty, long-haul transmission, small channel spacing and operating near zero dispersion wavelength. In this paper, a model is derived for the DRA carrier-to-noise ratio (CNR) caused by amplified spontaneous emission (ASE) using different pumping configurations: co-pumping, counter and bidirectional-pumping. The bit error rate (BER) is evaluated in the S-band from optical signal to noise ratio (OSNR). The simulation results show that, at 100 km fiber length, the CNR reaches its minimum value of 40 and 41 and 42 dB, in counter and bidirectional pumping, and 42 dB in co-pumping scheme. Moreover, the co-pumping provides the lowest BER in contrast to the counter pumping which achieves the highest BER among the three pumping schemes.