The Study Of High-power Single-wavelength And Multi-wavelength P-doped Raman Fiber Laser

With the rapid development of global communications, the ultra-high capacity of a new generation optical fiber communications system is demanded urgently. Therefore, as one of the vital components of optical communication systems, optical amplifiers are encountering a great challenge. Especially, Raman fiber amplifier (RFA) as a new generation amplifier has been thought as an ideal and potential solution. However, a key problem is that a suitable Raman pump source is very difficultly found. As a third-generation laser, fiber lasers are an excellent candidate as a Raman pump source, due to their advantages compared with conventional laser. Especially, because Raman fiber lasers (RFL) can be high-power output and the flexible lasing wavelength, they can perfectly meet the requirements of Raman pump sources and can replace the conventional diode laser.Based on the principle of stimulated Raman scattering (SRS) in single-mode fiber, the dissertation is focused on the study of RFL and multi-wavelength Raman fiber laser (MRFL).Firstly, the basic theory of SRS is introduced in details. The dynamics coupling equations governed the RFL are given and a Newton-Raphson-based shooting method is proposed to numerically solve it. In order to improve the efficiency and stability of the algorithm, the approximation solution of the coupling equations is used as an initially guessing value for the algorithm. It is shown that the computation time and stability can be significantly improved based on the improved algorithm.Secondly, the experiments of RFL pumped by the Nd: YVO₄ solid-state laser and double clad fiber laser (DCFL) are investigated, respectively. We obtain the output power of 1.15W/1484nm and the power fluctuation less than 6% in one hour pumped with a Nd:YVO₄ solid state laser. Furthermore, a higher output power of around 3.44W is also obtained when a DCFL is used as the Raman pump source. The optical conversion efficiency is about 28.1%. All experimental results are good agreement on the theoretical those.Finally, by use SRS of both P₂O₅ and SiO₂ in the P-doped fiber, it is the first time that a stable and spacing-adjustable phosphsilcate multi-wavelength Raman fiber in the O-band is achieved successfully. With the pump power of 2.5W, the multi-wavelength oscillations spaced at 0.8nm and 0.43nm have been observed, respectively.