Due to the all-time growing demand on higher network capacity it is required to increase the number of channels, and, therefore, to expand the bandwidth used for transmission in optical networks with wavelength division multiplexing. Together with increasing the number of channels, the optical attenuation, caused by division on the optical flow, becomes higher, especially in systems where optical splitters are used. Therefore, there is a need to compensate higher amount of optical attenuation over larger wavelength bandwidth. This can be achieved by using different types of optical amplifiers together, in such a way combining their benefits and partially compensating their drawbacks. During the last decade the advance in materials have resulted in devices capable of signal processing in the optical domain. Parametric amplifiers are a good example of such devices as, additionally to broadband signal amplification, this type of amplifiers can be used for all-optical signal processing. This Doctoral thesis covers the accomplished studies on implementation of hybrid optical amplifiers, as well as on the usage of parametric amplifier generated idler spectral components and the usage of parametric gain polarization dependence for all-optical signal processing. Based on the results introduces in this thesis, it is possible to assess the ability of hybrid amplifiers to increase the performance of existing discrete optical amplifiers. The obtained results also show, that parametric amplifiers can be successfully used in all-optical signal processing for increasing the number of carrier signals in WDM transmission systems and for emphasizing an optical component with a certain state of polarization from a combination of two orthogonally polarized optical components.