Study On The 2.8 ?m Pulsed Fiber Laser Which Based On TMDs-SAM

As a kind of saturable absorber,transition metal dichalcogenides have been widely used in pulse modulation of lasers.However,the use of transition metal dichalcogenides to prepared the saturable absorber mirrors for using in mid-infrared fiber lasers has rarely been reported.The 2.8?m fiber laser has important applications in many fields,and it is a hot spot in the research of mid-infrared fiber lasers.Due to the material properties of the Er³⁺:ZBLAN gain fiber,the output power of 2.8?m continuous laser is limited,then limit its application scope.In practical applications,the 2.8?m pulsed fiber laser with high energy and high peak power is urgently needed.The use of transition metal dichalcogenides for pulse modulation of mid-infrared fiber lasers have the potential to achieve high energy and high peak power 2.8?m pulsed fiber lasers.The study of 2.8?m pulsed fiber lasers which base on the transition metal dichalcogenides not only has an important academic significance,but also has an important practical application value.In this paper,the Er³⁺:ZBLAN fiber with high doping concentration is used as the gain medium of the laser cavity.Based on the saturable absorption mirror of transition metal dichalcogenides,we achieve the passively Q-switched and mode-locking pulsed fiber lasers.The main contents of our research on this topic are shown as following:1.Firstly,we summarize the passive pulse modulation methods of fiber lasers,the overview of the research on 2.8?m pulsed fiber lasers,the optical properties of Er³⁺:ZBLAN fibers and transition metal dichalcogenides.2.Two kinds of transition metal dichalcogenides aer prepared as the saturable absorption mirrors by chemical vapor deposition,the MoTe₂-SAM and the WSe₂-SAM.We obtained the2.8?m Q-switched pulse fiber laser base on the MoTe₂-SAM,which has a center wavelength of 2760.8 nm,an average output power of 76 mW,a pulse bandwidth of 4.1?s and a repetition rate of 83.95 kHz.At the same time,we obtained the 2788 nm Q-switched pulse fiber laser with the average output power of 100 mW which base on the WSe₂-SAM.The pulse bandwidth and repetition frequency were 0.5?s and 125.21 kHz,respectively.3.The WS₂-SAM was prepared by magnetron sputtering deposition method.We base on the WS₂-SAM achieve a passively mode-locking pulse of the 2.8?m fiber laser,which has an output center wavelength of 2750 nm,an average output power of 185 mW,and a repetition rate of 42.11 MHz.The slope efficiency is 8.2%.4.By optimizing the cooling method of Er³⁺:ZBLAN-doped fiber,a passively mode-locking fiber laser of 2.8?m which is based on the WSe₂-SAM prepared by chemical vapor deposition is achieved.It's average output power is 360 mW,the pulse width 30 ps,the frequency 42.43 MHz,and the spectral center wavelength 2789.6 nm.