Research On 1?m Mode-locked Fiber Lasers

Because of their compact structure,no need of water cooling and low cost,fiber lasers are wildly used in military,medical,industrial processing,precision measurement and so on.Ultra-short pulse fiber laser has been developed rapidly as a stable pulsed light source.The mode-locked fiber lasers based on semiconductor saturable absorber(SESAM)had become a research hotspot because of its compactness,self-starting and high stability.In this paper,the passive-mode-locked fiber lasers based on SESAM are simulated and experimentally verified.The research mainly includes picosecond fiber lasers,fiber amplifiers and femtosecond fiber lasers.The main work of the paper and the results obtained are as follows:1.The research background of this paper is put forward in the first place,and the basic principle and advantages and disadvantages of various mode-locking are analyzed and compared,and the research status of different mode-locking in recent years is introduced.2.The basic structure and principle of the Yb-doped fiber amplifier are introduced.The numerical model of the fiber amplifier is established.The physical process in the amplifier is simulated by MATLAB.The continuous wave input and the pulse input are analyzed concretely.In addition,this model can be directly applied to continuous wave fiber lasers.3.Based on the basic structure of the mode-locked fiber laser,the basic principle of the mode-locking and the forming process of the pulse are discussed.The loss,dispersion and non-linearity of the fiber are analyzed.Based on the nonlinear Schr?dinger equation,the numerical model of the mode-locked fiber laser based on SESAM is proposed.The mode-locked process is solved by distributed Fourier method(SSFT)and simulated.4.Based on the principle of passive mode-locking of SESAM,a picosecond mode-locked fiber laser was fabricated in the first place,and a picosecond pulse with a repetition frequency of 27.78 MHz and a Fourier transform-limited pulse width of 4ps was obtained.In order to obtain a higher output power to measure the actual pulse width,a fiber amplifier was constructed.The femtosecond mode-locked fiber laser was constructed.The femtosecond mode-locked fiber laser was fabricated by adding a grating pair for compensating cavity dispersion to obtain the femtosecond pulse with a spectral width of 3.62 nm and a Fourier transform-limited pulse width of 307fs.