Study On Multi-wavelength Erbium-doped Photonic Crystal Fiber Lasers Used For Gas Sensing

In recent years, Multi-wavelength erbium-doped fiber lasers aroused extensive attention in the past two decades, due to their potential applications in optical fiber communication system, fiber sensors, optical detection, microwave photonics, optical spectrum analysis and so on. However, the erbium-doped fiber is a homogeneous broadening medium at room temperature, which leads to fierce mode competition and makes it different to obtain stable lasing. Various techniques have been proposed to deal with the critical issue. The intensity-dependent loss is an effective technology to suppress the mode competition and obtain the multi-wavelength lasing at room temperature.Multi-wavelength Erbium-doped fiber laser based on four-wave mixing (FWM) is a technic that can get stable multi-wavelength laser output at room temperature. It utilizes FWM effect to mitigate mode competition in erbium-doped fiber (EDF). In this paper, a theoretical study on this type of laser is taken and analyzed the output characteristic.Firstly, this thesis introduces the operational principal of the multi-wavelength erbium-doped photonic crystal fiber laser currently adopted by domestic and abroad users and analyzes multiple models of erbium-doped fiber lasers, elaborating their advantages and disadvantages. Secondly, this thesis introduces the features of photonic crystal fibers and unfolds a discussion on splicing photonic crystal fibers. And through further theoretical analysis on multi-wavelength erbium-doped photonic crystal fiber lasers, this thesis elaborates the feasibility of building the lasers theoretically. In the end, this thesis proposes to use a kind of high-nonlinearity photonic crystal fiber as the gain medium to build a kind of laser with circular cavity structure, which, through the four-wave mixing effect of the high-nonlinearity photonic crystal fiber and the accurately-controlled polarization controllers, effectively suppresses the mode-competition effect of erbium-doped fibers and finally realizes stable multi-wavelength output of lasers at room temperature.