"In this thesis, two different main projects were implemented. In the first project, we studied the experimental behavior of nonlinear Raman scattering in a single-mode Nufern 980-HP silica fiber of 1-km in length pumped a 1064-nm. We reconsider some approximations and physical facts that construct the model of Raman amplification. In the second project, we present the study and the results of the modification of a Raman fiber laser. We propose this approach to be used when high stability, high efficiency, and single-line emission is desired in Raman fiber lasers."