A low noise-figure hybrid optical amplifier by using second-order stimulated Raman scattering

The requirement of amplification for wide-bandwidth, compensation of attenuation for long-distance, and high-speed communication generates a need for highly efficient amplifiers. There are several types of amplifiers, such as semiconductor and fiber amplifiers. However, Raman amplifiers have some benefits over others, such as being less expensive and having high-gain bandwidth products. A low noise figure and high and flat gain are advantages of second-order Raman amplifiers over first-order amplifiers. There are various ways to implement second-order Raman amplifiers by using dispersion compensating fibers (DCF) or single-mode fibers (SMF) of different configurations. In this paper, a novel hybrid amplifier has been proposed. This is a combination of an erbium-doped fiber amplifier (EDFA) and a Raman amplifier. Here, the Raman amplifier uses second-order Raman pumping for amplification, which is based on second-order stimulated Raman scattering (SO-SRS). Here, the Raman fiber is a single-mode fiber (SMF). Simulation has been done for output power, gain, and noise figure (NF). A comparison of first-order and second-order hybrid amplifiers has been done for the above parameters. Also, the proposed second-order hybrid amplifier has been compared to one of the previous versions. The results obtained show improvement in terms of output power, gain, and NF. The lowest NF obtained for the proposed amplifier is 4.42 dB at Raman length of 15 km and second order pump power of 450 mW.