Study And Realization Of Multi-Pumped Fiber Raman Amplifiers

As the information globalization and the demands for high capacity services constantly increase, the optical communication market comes to revive gradually. The ultra-long haul and high capacity DWDM optical transmission networks which will be the foundation of the next generation information high way, grow rapidly and gain much attention.In this dissertation, a cost-effective C+L band, 60nm bandwidth, 4-wavelength pumped FRA has been produced. We design and realize pump drive circuits, which are the key components of the whole systems, and derive some helpful conclusions on FRAs' design, realization and system application. The primary achievements are as follows:1) The device requirements of optical amplifiers and system applications of FRA-amplified DWDM systems are studied. At the same time, several important driving forces of ultra-long haul and high capacity DWDM systems are also proposed and analyzed.2) The characteristics of SRS gain coefficient are studied, and an important conclusion is achieved: the Raman gain coefficient is dependant on fiber types and pumps' wavelengths. The method of fiber selection is also proposed.3) The average power analysis algorithm is adopted to solve the power coupling equations of FRAs, and two-point boundary value problems in backward pumped FRAs are solved. The pump configuration method in multi-pumped FRAs is demonstrated. Moreover, output gain spectra, pump and signal power distributions in the transmission fiber are calculated. At last, the noise and transient impacts of FRAs are also introduced.4) The realization of pump drive circuit in FRAs are discussed. The realization method, some practical problems and the methods for next-step performance improvement of constant current source, backlight monitor, temperature control circuit are described.5) An FRA experimental prototype is made. By using this amplifier, EDFA plus Raman hybrid transmission experiment is implemented. The conclusion drawn from the experiment is useful for the next step experiments.