2?m Band Thulium-doped Multiwavelength Fiber Laser

The 2?m fiber laser covers a wide range of applications in the fields of laser medical,free space optical communication,mid-infrared pump and so on.It is usually obtained by laser pumping thulium doped or holmium doped fiber to get 2?m band gain spectrum,through the filter to produce multi-wavelength laser output.In this paper,thulium doped fiber is used as the gain medium,and several different tunable wavelength thulium-doped fiber lasers are designed and analyzed.The output of multiwavelength laser and multiwavelength mode-locked laser are realized respectively in 2?m band.The main contents are summarized as follows:1.The gain spectrum characteristics of thulium doped fiber are studied.A gain spectrum of 1750-2200 nm was obtained by pumping the thulium-doped fiber using a 1565 nm semiconductor laser.The influence of different pump power and fiber length on the output characteristic of gain spectrum is analyzed.2.Two kinds of multiwavelength fiber lasers based on multi-mode interference filter are designed.The Sagnac ring and the multi-mode interference filter are used to obtain the tunable output of 3nm-80 nm with dual-wavelength interval.The laser output can be obtained in 1-4 wavelengths with different pump power and polarization state.By combining the multimode interference filter with the comb filter,a laser output of 26.7nm with double wavelength interval tuning range of 7.5MHz is obtained.3.A 2?m wavelength multi-wavelength fiber laser based on nonlinear polarization rotation is designed and stable laser outputs of 1-5 wavelengths are obtained.By increasing the birefringence fiber in the cavity and enhancing the birefringence effect in the cavity,a single-wavelength tunable output of 127 nm can be obtained,and the laser output of 1-5 wavelengths can be realized under different polarization states.4.A 2?m wavelength multi-wavelength mode-locked fiber laser is designed.The pulse output of pulse width is 72 ps and the repetition rate is 12 MHz.Through the optimization of the cavity nonlinear effect,a dual-wavelength mode-locked output with tuning range of 87 nm is obtained.The pulse width is 75 ps and the repetition rate is 3MHz.