| Ultra-short pulse fiber lasers have more advantages, such as all-fiber structure, simple thermal management, better beam-quality, high conversion efficiency and relatively low cost. So they have extensive application in medical, military, industrial processing, high-speed optical fiber communication, precision measurement and other fields. All-fiber ulta-short pulse lasers have been studed in this thesis, and they mainly include all-fiber picoseconds laser oscillator, all-fiber laser amplifier and all-fiber chirped pulse amplifier, respectively. In addition, the all-fiber supercontinuum laser has also been demonstrated. In this thesis, the main research work and results are as follows:1.Ultrashort pulse laser oscillators have been studied theoretically and experimentally, which mainly include all-fiber picoseconds laser oscillator and all-solid state picoseconds laser oscillator. All-fiber laser oscillators have been demonstrated by three kinds of passive mode-locked technology: SESAM mode-locking, NPR mode-locking and SESAM/NPR mode-locking technology. Their output pulse-widths are 4 ps, 300 ps and 20 ps, respectively. Meanwhile, the transmission-characteristic of the pulse in NPR mode-locked fiber laser has been studied in theory using the coupled nonlinear Schr?dinger(CNLS) equation, and the harmonic passively mode-locking has been realized in SESAM/NPR mode-locked fiber laser. All-solid state picoseconds laser oscillator has been obtained by SESAM passive mode-locked technology. A novel resonator structure with large mode field space is introduced to solve thermal lens effect and then a single-beam-output picosecond pulse laser is achieved without inserting any other laser output elements in laser resonator. Its average output power is 10.5 W. In addition, a complete evolution process of pulses from Q-switched mode-locking to continuous wave(CW) mode-locking has been observed for the first time.2.All-fiber laser amplifier has been demonstrated using MOPA amplification technology. 100 W-picosecond pulse lasers produced in 30 μm and 10 μm core double-clad fibers have been studed theoretically and experimentally. For 10/130 μm doped fiber, we make a theoretical simulation firstly based on four-level rate equation(FLRE) and nonlinear Schr?dinger equation(NLSE), then in experiment, 100 W of average output power is obtained in 10 μm fiber core with the length of 6.5 m. For 30/250 μm doped fiber, 120 W pulse laser has been obtained in all-fiber laser amplifier with the pulse width of 620 ps, and its light-to-light conversion efficiency is up to 83.9%.3.All-fiber chirped pulse laser amplifier has been demonstrated using reflection-grating and transmission-grating as a compressor, respectively, and the SMF stretcher is imtroduced in the system. For the reflection-grating experiment, the compressed pulse laser output power is 100 mW and its pulse width is 720 fs. For the transmission-grating experiment, the 2.5 W/680 fs compressed pulse laser and 6.5 W/613 fs compressed pulse laser have been obtained, respectively.4.All-fiber supercontinuum laser has been demonstrated by the way that the pulse laser pumping the nonlinear PCF. Two kinds of nonlinear PCFs have been introduced in the experiment: the round-arrangement air hole PCF and the hexagonal-arrangement air hole PCF. Finally, 30 W and 36 W average-output-power supercontinuum laser are obtained corresponding to spectral broadening range from 550 nm to 1650 nm and 500 nm to 1650 nm, respectively. The pulse width of the supercontinuum laser is about 244.95 ps, and the pulse trains are very uniform. In addition, it shows good time coherence in broadening wavelength-band.
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