Multi-pump discrete Raman amplifier for CWDM system in the O-band

We demonstrate theoretically that discrete Raman amplifiers operating in the O-band region (1260-1360 nm) are more efficient than in any other band if we consider the fiber attenuation. Compared with the C-band (1530-1565 nm), the net gain is 3 dB higher. We present also theoretically two types of discrete Raman amplifiers which can be used in the O-band with a course wavelength division multiplexing system. The first amplifier has a bandwidth of 70 nm that was designed with four pump lasers operating at 12XY nm. The second one has a bandwidth of 100 nm and needed six pump lasers to obtain a flattened gain across the O-band. In addition, we have analyzed the gain saturation in both optical amplifiers.