Research On All Fiber Multi-wavelength Q-switched Pulsed Fiber Laser

As a part of the fiber laser clan,multi-wavelength Q-switched fiber lasers have potential application value in high-precision fiber detection radar ranging systems and biomedicine.It is one of the central issue of scientific research recently.This thesis is an experimental study of multi-wavelength Q-switched fiber lasers.Three different structures of multi-wavelength Q-switched fiber lasers are designed using different Q-switched components and filters.The content of this article focuses on the discussion of the following three types of lasers:First,an actively multi-wavelength Q-switched fiber laser based on electro-optic modulator(EOM)and Sagnac ring interferometer is studied.First,we analyze the filtering mechanism of Sagnac loop.Then,we carry out experiments through the given experimental device,and analyze the experimental results.When the input power is 160 m W,we obtain a 50.06 ?s double pulse and analyze the generation principle,focusing on the pump power and modulation frequency.And the influence of bias voltage on average power and double pulse.Second,a multi-wavelength Q-switched fiber laser based on erbium-ytterbium co-doped fiber(EYDF)as a saturable absorber and a parallel Bragg grating(FBG)as a filter is studied.First,we analyze the nonlinearity of the unpumped EYDF saturable absorber(EYDF-SA).Then given the experimental device and experimental results,a single wavelength of 1545.63 nm and dual wavelengths with center wavelengths of1545.63 nm and 1553.6 nm are obtained.Generate a pulse with a maximum repetition frequency of 24.27 k Hz,and the narrowest pulse width is 5.48 ?s.The pulse Q-switching characteristics corresponding to dual wavelengths are also discussed.Third,a multi-wavelength Q-switched fiber laser based on EYDF-SA and a parallel Sagnac interferometer as a multi-wavelength gating device is studied.First,the theory involved in the parallel composite Sagnac interferometer is analyzed,and then the experimental device is given.The single-wavelength tunable,20-45 m W is dual-wavelength tunable,and the three-wavelength tunable of 45-50 m W are obtained within 15-20 m W.Finally we analyze the experimental results.