Multiwavelength Erbium-doped Fiber Ring Laser Based On Nonlinear Effect

Multiwavelength-operating devices for wavelength-routed optical network have attracted considerable interest as the capacity of wavelength-division multiplexing (WDM) systems extremely increases. Multiwavelength erbium-doped fiber ring lasers (MW-EDFRLs) have versatile applications in dense wavelength division multiplexing (DWDM) systems, optical fiber sensors, optical instrument testing, microwave photonic systems and high resolution optic spectral analyzer because they have a variety of advantages such as simple structure, low cost and insertion loss. We conduct some theoretical simulations of the multiwavelength lasing process by using MatLab software and experimently demonstrate a MW-EDFRL based on nonlinear effect in the highly nonlinear fiber (HNLF). The main parts of this dissertation are as follows:(1) Based on deeply investigation of the current studying of mitigating homogeneous line broadening (HLB) effect of erbium-doped fiber (EDF) to realize MW-EDFRLs, we add a highly nonlinear fiber in the ring cavity, in which the degenerated FWM effect and cross-phase modulation (XPM), self-phase modulation (SPM) between the waves can be used to suppress the cavity mode competition resulting from HLB effect,and then realize multiwavelength lasing.(2) Based on the theory of interaction between light and matter, we introduce the theory of erbium-doped fiber amplifier (EDFA) and the selection of the pumping sources; we introduce the property of HLB of EDF and the theory of mode-competition in the homogeneous broadening fiber laser; based on the theory of rate equations and power propagation equations of erbium-doped fiber laser (EDFL), we set up the numerical model of MW-EDFRL.(3) Considering the experiment design, we propose and theoretically analyse the key technologies of realizing MW-EDFRLs: combfilter based on polarization-maintainning fiber (PMF) used to select lasing wavelengths and nonlinear effect used to suppress HLB in EDF.(4) We modularize the dual-wavelength-EDFRL system, simulate it by using MatLab software and compare the differences between the cases of adding and taking out HNLF in the ring cavity. The simulation results indicate that the nonlinear effect including FWM, SPM and XPM in the lasing cavity can perfectly mitigate the HLB effect of EDF. (5) Considering the present experiment condition, we carry out some experimental research and realize stable three-wavelength lasing at most when we use 3dB-variation range of power as the stabilization criterion.