Study On Erbium-doped Fiber Laser With SB/SnS As Saturable Absorber

Compared with solid-state lasers,fiber laser have good beam quality and compact structure,and the external environment has little influence on the fiber laser because the laser emission was bounded into the fiber.In addition,the fiber has a large specific surface area,with excellent heat dissipation.Pulsed fiber lasers have important applications in the fields of fiber communication,defense and military security,medical health,micromachining,marking,welding and cutting.Using saturable absorber(SA)as a key device for passively Q-switched and passively mode-locked technique is an important means for generating ultrashort pulsed lasers with nanosecond(ns),picosecond(ps),and even femtosecond(fs).Antimonene(Sb)and tin sulfide(SnS)as new twodimensional materials,which have the advantages of ultrafast recovery time,high damage threshold and high stability,and can be made into a saturable absorber(SA)that apply in passive Q-switched and passive mode-locking laser to obtain ultrafast pulse.In this article,Sb and SnS were used in a ring erbium-doped laser cavity,and successfully obtain mode-locked fiber laser based on the antimonene-saturable absorber(Sb-SA)and mode-locked fiber laser and Q-switched fiber laser based on the tin sulfide-saturable absorber(SnS-SA),respectively.In the experimental results,the mode locking,bound mode locking,harmonic mode locking and Q-switched are observed.The main contribution of this thesis is as follows:1.Mode-locking and Q-switched technique in fiber lasers are reviewed,and the feasibility of Sb and SnS as SA used in the mode-locked and Q-switched fiber lasers are demonstrated in detail;2.Basic principle of passive mode locking and passive Q-switching are reviewed,and basic principle and measurement method of saturable absorber is introduced.The production process of the two-dimensional materials of Sb and SnS were introduced in detail.The two kinds of materials were characterized by atomic force microscopy(AFM),Transmission electron microscope(TEM)and Raman spectra by chemical characterization;3.Sb-SA-based passive mode locking is realized in erbium-doped fiber laser with the pulse width as short as 552 fs and the fundamental repetition rate up to 10.27 MHz;4.SnS-SA-based passive mode locking is realized in erbium-doped fiber laser,whose pulse width is 656 fs and the repetition frequency is 8.37 MHz.By adjusting the pump power and the polarization controller properly,the harmonic mode-locked is realized,corresponding to the 20 th harmonic of fundamental repetition frequency.In addition,a new SnS-SA with specific parameters is prepared to realize Q-switched pulse in the same laser cavity with repetition frequency tunable from 36.36 kHz to 65.19 kHz.