Pulse Characteristics Of High Energy Soliton In 2?m Mode-locked Fiber Laser

2 ?m mode-locked Tm-doped fiber lasers have been widely investigated in many fields.However,it is still difficult to realize soliton pulse with high energy in a full-fiberized Tmdoped ring cavity due to the difficulty of dispersion management.Also,there are relatively few studies on the output characteristics of high-energy soliton pulse.Therefore,in this thesis,using dispersion management,the generation and output characteristics of high-energy soliton pulse in 2 ?m mode-locked fiber lasers are studied.The specific research contents are as follows:1.A nonlinear polarization rotation(NPR)mode-locked fiber laser was designed to research the energy improvement of conventional soliton in the anomalous dispersion regime,and ultra-high numerical aperture(UHNA)fiber with the highest compression efficiency and lowest power loss was selected for dispersion management.When the cavity dispersion is-0.151 ps2,the evolution from a conventional soliton pulse to a Gaussian pulse with high pulse energy can be achieved.The output pulse characteristics of the Gaussian pulse were analyzed.The pulse width and pulse energy of Gaussian pulse are 517 fs and 1.38 n J,respectively.Compared with the conventional soliton pulse,the pulse energy is increased by 1700 %.2.A strong dispersion management resonant cavity based on NPR was designed to study high-energy soliton pulses with narrower pulse widths.First,in the near-zero dispersion regime,wavelength-switchable and tunable dispersion-managed soliton pulses were realized.The wavelength can be tuned from 1957 nm to 1965 nm and 1979 nm to 1984 nm.The minimum pulse width is 371 fs and the maximum pulse energy is 0.209 n J.Then,further compensating the cavity dispersion to the normal dispersion regime,dissipative soliton pulse with pulse width of 355 fs and maximum pulse energy of 0.592 n J was obtained.And then,the output characteristics of two solitons were analyzed.3.Research on mode-locking pulses with higher energy based on nonlinear amplifying loop mirror(NALM)mode-locking.First,a noise-like pulse with maximum pulse envelope width of 1.2 ns and maximum pulse energy of 3.4 n J was achieved in the pure anomalous dispersion regime.The output characteristics were analyzed.Second,the dispersion management method was used to achieve noise-like pulse with a higher energy while maintaining the pulse envelope and repetition frequency,the pulse energy can be increased to 4.97 n J,an increase of more than 46 %.