Research On The All Fiber Filter Based On The Mode Interference And Its Application In The Dual-wavelength Erbium-doped Fiber Laser

Compared to the conventional lasers, the fiber laser owns many unique advantages and is becoming one of the most important lasers. Because the dual-wavelength fiber lasers can be widely used in generation of microwave signal, self-mixing active sensor and optical fiber communication, it have attracted many researchers’interest. If the two oscillated wavelength of the lasers can be switched and the wavelength spacing can be tuned, due to the flexible output, this kind of fiber lasers will be more meaningful. This paper researches on a switchable dual-wavelength erbium-doped fiber laser based on the novel all fiber filters and the works are carried out as follow.(1) This part introduces the development of the fiber laser and the significance of the study on the dual-wavelength fiber laser.(2) The basic theory of fiber lasers, including the interaction of light and material, the generation of laser, the energy level of the erbium-doped fiber and the cavity of erbium-doped fiber laser, is reviewed. The dual-wavelength fiber lasers based on the different filters are discussed.(3) This part study on a dual-wavelength erbium-doped fiber laser based on the two-taper Mach-Zehnder interferometer(MZI) filter. Firstly, the fabrication of the MZI filter and simulation of the mode excitation in the filters are discussed in detailed. Then, using the two-taper MZI filter in the ring cavity, dual-wavelength oscillation is achieved. By controlling the curvature of the two-taper MZI filter, a switchable dual-wavelength can be realized at last.(4) This part study on a dual-wavelength erbium-doped fiber laser based on an ultra-compact all fiber filter. The filter is composed of a core offset in-line MZI filter and a fiber Bragg grating(FBG), the FBG is written in core offset MZI filter. At first, the principle of the in-line MZI filter is introduced and its function is simulated. Secondly, according to the theoretical analysis, the characteristics of the filter is proved in experiment. At last, the ultra-compact filter is used in the laser ring cavity to achieve a switchable dual-wavelength output. By stretching the filter, the wavelength spacing can be increased.