The Investigations On Characteristics Of Broadband Er³⁺-doped Superfluorescent Fiber Sources

The erbium-doped superfluorescent fiber source (SFS) is widely applied in dense wavelength division multiplexing(DWDM), fiber sensor systems, fiber gyroscopes and so on , for its broad spectral range, high output power and stabile mean wavelength。The former researches were mainly on C-band (1525-1625nm). However, recent demand for immediate expansion of the fiber optic communication window has led more attentions to the development of L-band (1565-1625nm) and C+L-band (1525-1625nm). In this paper the stable L-band SFS and flat C+L-band SFS are researched. The main work in this paper contains three parts.The first part contains Chapter one, two and three. In this part after the analysis of the characteristics of erbium-doped SFS, the development of SFS was introduced. After introducing the principle of amplified spontaneous emission (ASE) and discussing the theory model of erbium-doped SFS, the propagation equations and the rate equations were summarized. In Chapter three the fundamental to generate L-band SFS was introduced first. Then the simple double pass forward (DPF) configuration was investigated theoretically. The experiment was done under the guidance of the theoretical results. It's proved that the experimental results are in good agreement with the theoretical results.In the second part, a two-stage double pass forward(DPF) configuration of two-stage L-band SFS was put forward and investigated. Through simulation it was found that under the optimum fiber length rate and pump power rate, the pumping efficiency and output linewidth of two-stage DPF configuration were much better than those of one-stage DPF configuration. In addition, it was also found that the mean wavelength of two-stage DPF configuration was insensitive to pump power. The following experiment proved this characteristic.Chapter five was the third part, which investigated C+L-band SFS. After learning the principle to generate C+L-band, we found that two-stage DPF configuration could also generate flat C+L-band SFS by choosing optimum fiber rate and pump rate. A series flat C+L-band SFS with bandwidth over 80nm were attained in the experiment.