The Watt Level Pico-second Fiber Laser In MOPA Construction

The ultrashort pulse has widespread applications in areas such as industry, medicine and fiber communication. Ultrashort pulse passively mode-locked fiber laser is studied in the article.It is very important to set up an excellent seeding resource because the speciality of the passively mode-locked fiber laser based on MOPA construction depends on the seeding resource's speciality. We set up different seeding resources using two SESAM whose relaxation time are 9ps and 500fs, respectively, and using different fiber gratings with reflectivity of 10% or 90% or 99.86%. Experiments of seeding resource with different cavity's length of 4.5 meter and 10 meter are also accomplished. Output power, waveform and spectrum are compared. The optimized configuration is given.The influences of the seeding resource, which cavity's length is 4.5 meter or 10 meter, to the first amplifier and the second amplifier are compared. The influence to the speciality of the first amplifier which is caused by the length of the Yb-doped fiber is compared. The length of the Yb-doped fiber is 0.35 meter or 0.6 meter or 1 meter. The optimal length of the Yb-doped fiber is between 0.6 meter and 1 meter. The factors which restrict the speciality of the amplifier are presented and corresponding conclusions are drawn up.An optimized watt level passively mode-locked ps fiber laser based on MOPA construction is set up. The seeding resource is passively mode-locked steadily when the pumping power is 54mW. The highest average output power is 8.5mW, the repetition frequency is 24.5MHz, the pulse width is 30ps. The highest average output power of the first amplifier is 112mW. The highest average output power of the second amplifier is 1.9W.