| Optical fiber-based micro-nano devices formed by compounding advanced materials such as metal/metal compounds,dielectric micro-nano structures,and two-dimensional(2D)materials with optical fibers have become one of the hot research fields in recent years.At present,standard micro-nano structure fabrication techniques not only require expensive equipment,time-consuming,but also are limited by "one-by-one" fabricating process,resulting in low yields.Therefore,developing a new technology to efficiently prepare micro-nano materials with fiber and exploring its application in ultrafast fiber laser generation has important research significance and application value in both basic research and economic benefits.This paper mainly studies the preparation of three different materials combined with optical fiber tip(OFT),and used as a saturable absorber(SA)in a passively modulated fiber laser to analyze and study its different laser pulse generation characteristics.The specific research contents are as follows:1.Passive mode-locking application of plasmonic Ti N NPs: In this experiment,Ti N films were prepared by drop-injection method and inserted into the Erbium-doped fiber laser(EDFL)annular cavity as SA.The pulse evolution and dynamics process in two states: mode-locking and Q-switched mode-locking(QS-ML)were observed experimentally by advanced dispersive Fourier transform technique.The QS-ML mode was operating in the EDFL cavity,and the "breathing" frequency of the pulse spectrum evolving in real time was found to correspond to the periodic variation of the Q-switched pulse.2.Preparation of SA based on Hexagonal Boron Nitride(2D h BN)thin film material and its application of passive Q-switching: We first successfully transferred the single-layer h BN film floating at the water/air interface onto the OFT by using the self-sedimentation technique.2D h BN as SA realized passive Q-switching in the ring EDFL cavity.The Q-switched laser initiated by the2 D h BN fiber exhibited the output power increased from 0.325 to 2.25 MW,and the repetition rate increased from 29.41 k Hz to 55.5 k Hz when the pump power increased from 45.1 m W to 203.9m W.3.Fabrication of optical fiber end-face golden triangle array structure SA and its optical modulation application: We developed and improved the fabrication of high-quality,large-area gold triangular array structures based on Langmuir-Blodgett self-assembled Nanosphere Lithography on OFT.This fabrication technique has low cost and high yield.In the experiment,up to 36 functionalized fibers can be fabricated at the same time.It was found that the gold triangle structure fabricated by different sizes of polystyrene nanospheres exhibited highly tunable surface plasmon resonance in linear transmission spectrum and large modulation depth in nonlinear transmission spectrum(maximum: 11.5%).The experimental results shown that when the surface plasmon resonance of golden triangle array structure was close to 1.5 μm,the golden triangle array structure as SA was realized the mode-locked pulse laser output with ps pulse width(～3.7 ps),high power(>10 m W)and signal-to-noise ratio close to 50 d B.Our research provides new ideas for efficiently preparing functionalized fibers and reducing manufacturing costs,and also provides a new experimental system for studying the generation of all fiber high-power ultrafast pulse laser. |
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