Study On Fiber Lasers With WSe₂ As Saturable Absorbers

Pulsed fiber laser has a wide range of applications in optical fiber communication,bioengineering and medical equipment,military defense security,industrial making,and so on.In fact,the saturable absorber is always the hot spot in pulsed laser study,a qualified saturable absorber can effect the quality of beam and light pulse,and sometimes decide the experiment's success or failure.As the traditional saturable absorber?for example semiconductor saturable absorber mirror?exist expensive,complex production process,high coupling loss and other defects,limiting the development of ultrafast photonics.Therefore,researchers explore other new nanomaterials?such as SESAM,carbon nanotubes,grapheme,topological insulators,transition metal dichalcogenides,black phosphorous,etc?,these new nanomaterials have different merits and demerits,which push pulsed laser study forward.In this work,we fabricate a microfiber-WSe₂ device,by using this new SA as a mode-locker,soliton pulse generation is achieved,which suggests that the large-areaWSe₂ atomic layers can widely use for ultrafast photonics.The main work of this paper is as follows:1.We briefly describe the advantages,applications and history relative to traditional bulk solid-state lasers.Introduce the historical evolution of the saturable absorber,microfiber and2D TMDCs.2.We fabricate some microfiber-WSe₂ and characterization.Including OM,AFM,TEM,RS,PL,and EDS.By using a Raman spectrumter,three characteristic peaks ofWSe₂ are located at 252cm^-1,262cm^-1 and 309cm^-1.And then give a nonlinear saturable absorption curve.The modulation depth is measured to be 54.5%at 1550nm,which is the best compare to other study.3.Based on theWSe₂ mode-locked erbium-doped fiber laser?EDFL?:In this experiment,we fabricate a erbium-doped fiber ring laser to abtain output pulse by changing dispersion.When the total cavity length is 80m,the measured signal-to-noise ratio of mode-locked pulse is 66dB,the center wavelength of the spectrum is near 1570.8nm,and the bandwidth of 3dB is about 2.1nm,pulse width is 1.2ps;when the total cavity length decreases to 18m,the measured signal-to-noise ratio of mode-locked pulse is 70dB,the center wavelength of the spectrum is near 1569.5nm,and the bandwidth of 3dB is about 3.5nm,pulse width is 702fs;when the total cavity length decreases to 14.77m,the measured signal-to-noise ratio of mode-locked pulse is 80dB,the center wavelength of the spectrum is near 1556.4nm,and the bandwidth of 3d B is about 6.06nm,and the pulse width decreases from 702fs to 477fs.4.Based on the above experiment:We briefly introduce aWSe₂ mode-locked Thulium-doped fiber laser?TDFL?.To testWSe₂ relible can operate at 2?m,the measured output pulse width is 1.16ps,which is the first mode-locked Thulium-doped fiber laser by usingWSe₂ in the world.5.To conclude this paper and give ideas to look forward.