Study On Dual-Wavelength Ring Cavity Er-Doped Fiber Laser

Multi-wavelength laser can provide the necessary light sources for many channels and make the transmitter more compact and economic. Therefore they have potential for various applications such as dense wavelength division multiplexing (DWDM) systems, laser ranging, spectrum analysis, optical fiber sensing etc. Multi-wavelength fiber laser has become a research focus in laser domain recently.In this paper, combined the absorption and emission characteristics of rare-earth-ions, the steady-state rate equations model of dual-wavelength erbium-doped ring fiber laser (DW-EDRFL) is established, and the influences of pump power, the upper level population density, the threshold pump power and the attenuation of VOA on output characteristics are numerically simulated as well. The results indicate that using fiber Bragg grating (FBG) as the mode selection elements, its peak wavelength and reflectivity decide the output of the fiber laser. As different loss corresponded to different cavities between the two FBGs, the variable attenuator are used to finely adjust the loss of the corresponding wavelength in order to balance gain and loss, to achieve oscillation at single- or dual-wavelength. The useful results which provide theoretical basis are obtained.The simulation model of DW-EDRFL based on optisystem is established. After choosing components and setting their parameters according to the characteristics of components and requires of simulation environment, the simulation results can be observed from optical spectrum analyzer. The results indicate that the optical attenuator plays an important role in the whole ring cavity. Through adjusting the attenuation of VOA we can achieve the single- or dual-wavelength output. The analysis process of theory and the numerical simulation results are finely demonstrated.