Study On Dissipative Soliton Mode-locked Fiber Laser Based On Lyot Filter

The ultrashort pulse generated by the mode-locked fiber laser is widely used in scientific research,industrial processing,military,biological,medical and other fields,due to the high power and high energy.The all-normal dispersion mode-locked ytterbium-doped fiber laser can produce dissipative solitons that can withstand higher nonlinear accumulation and higher single-pulse energy,making it attract the attention of many researchers in the field of scientific research.We combined a bandwidth-tunbale Lyot filter with a semiconductor saturable absorber to build an all-fiber all-normal dispersion Ytterbium-doped mode-locked laser.Utilizing the adjustable bandwidth of the Lyot filter,the tunable dissipative soliton pulse is realized.The content of this article is as follows:1.Summarize the characteristics,application and development history of ultrashort pulse laser.The characteristics,advantages and development status of all-normal dispersion ytterbium-doped mode-locked fiber lasers are emphatically introduced.2.Introduce the basic principle of ytterbium-doped mode-locked fiber laser,including mode-locking principle,mode-locking method,pulse shaping method and commonly used filters.Based on the averaged Ginzburg-Landu equation,deduce the steady-state solution of dissipative solitons,and analyze the effects of dispersion,nonlinearity,gain,filter bandwidth,and saturable absorber parameters on the properties of the dissipative soliton.3.The RP FIBER POWER software is used to numerically simulate the all-normal dispersion ytterbium-doped fiber laser,and analyze the effects of dispersion,nonlinearity,gain,and filter bandwidth on the properties of the dissipative soliton.The influence of different filter positions of the cavity on the dissipative soliton is given.4.We have implemented wavelength-tunable in an ytterbium-doped passively mode-locked fiber laser using semiconductor saturable absorber and Lyot filter.The Lyot filter consists of a single mode fiber（SMF）spliced between two polarization fibers（PMF）,the fiber length of PM₁,SMF,PMF₂are 10cm,70cm,20cm respectively,chosen by numerical simulation in section 4.In our experiment,benifiting from the birefringence-induced filtering effect,the central wavelength of the dissipative solitons could be tuned from 1020nm to1041nm with a range of 21nm.While the central wavelength of the DSs is 1035nm,The spectral width tuning from 1.3nm to 5.87nm was obtained by changing the pump power and filter bandwidth.And by properly adjusting the filtering bandwidth,the second harmonic mode-locking can be observed when the pump power is 130m W,and the three-pulse cluster and five-pulse cluster dissipative soliton output can be observed when the pump power is140mW.