Research On Mode-locked Pulse Thulium-doped Fiber Laser

2?m fiber laser can be generated by mode-locked thulium doped fiber laser.2?m fiber laser has high performance in biological tissue ablation or cruor,and can be wildly used in minimally invasive surgery.2?m fiber laser can pump telluride or sulphide and get 2.0~5.0?m broadband super continuum laser which can be used in detection of toxic gases lidar and electro optical countermeasures,gradually become the focus as a new laser light.In this paper two different types of passively mode-locked thulium doped fiber laser are studied,2?m pulse laser and multi-wavelength laser are realized in the experiment.The experimental structure and results is demonstrated.There are four major parts in this study:1.A passively mode-locked thulium doped fiber laser based on nonlinear polarization rotation effect is studied.Mode-locked pulse laser and tunable wavelength laser is achieved in the experiment.The pulse width is 617 ps,and repetition frequency of the pulse laser is 3.178 MHz and tunable multi-wavelength laser is obtained with 33 nm tuning range,the wavelength number of the laser is from 1 to 5.The principle of thulium doped fiber laser based on nonlinear polarization rotation effect operating in passive mode locking and multi wavelength is analyzed.2.The thulium doped fiber laser with nonlinear polarization rotary cavity structure is improved.Tunable pulse laser with 94 nm tuning range is achieved.The wavelength of the tunable pulse laser is from 1835 nm to 1929 nm.The repetition frequency of the pulse laser is 3.178 MHz and the pulse width is 75 ps.3.The dissipative soliton resonance erbium doped fiber laser based on nonlinear amplifying loop mirror is studied.In the cavity without Shaisa compensation,we realized the dissipative soliton resonance square wave pulse laser output.The pulse width is extended from 700 ps to 3.7ns and the single pulse energy of the pulse laser is increased from 5.2 nJ to 27.4 nJ.The pulse repetition frequency is 3.65 MHz and the wavelength is 1527 nm.The structure has good stability of output power and wavelength.4.The mode-locking thulium-doped fiber laser based on nonlinear amplifying loop mirror is studied.We have obtained the pulse laser output running at 2 ?m band.The pulse repetition frequency is 4.23 MHz and the pulse width is 73 ps.