Study On Mode Locked MOPA Picosecond Pulsed Fiber Laser Based On SESAM

Fiber laser has many advantages such as small size,simple structure and high stability,which make it widely used in various fields.In recent years,with the expansion of the application field of pulsed fiber lasers,the demands of the output pulse width and peak power are gradually increased.The MOPA-structured pulsed fiber laser can retain the high quality laser characteristics of the seed source and obtain higher peak power and pulse energy,which has become one of the main research hotspots.In this paper,the development and application of pulsed laser are briefly introduced,the development status of mode-locked fiber lasers and amplifiers at home and abroad is described.The principle of mode-locking,the mode-locking technology of semiconductor saturable absorber mirror and the evolution process of pulse in amplifier are introduced.The key points of MOPA amplification technology are analyzed,and the pulse transmission equation of SESAM mode-locked fiber laser and amplifier is given.In the part of numerical simulation,the effects of intracavity dispersion,nonlinear effect,gain and loss on output pulse characteristics and the effect of chirp carried by seed light on amplification pulse characteristics of SESAM mode-locked fiber laser are analyzed.In the part of experiment,a mode-locked fiber laser with MOPA structure is built,the seed source part,according to the theoretical simulation,select length of 0.2m ytterbium doped fiber as gain medium,SESAM as clamping device,when the pump power is 60 MW,a picosecond pulse laser with a central wavelength of 1060.58 nm,a repetition rate of 37 MHz and an average power of 2.06 MW is obtained,after the output of the seed source is pre amplified,the pulse width is 12.51 ps.After the output of the mode-locked fiber laser seed source is amplified by two-stage fiber,a pulsed laser with an average power of 1W,a repetition frequency of 37 MHz and a pulse width of 17.2ps is obtained.