Study Of Nonlinear Optical Properties And Application On Titanium Carbon Compounds

Transition metal carbides/nitrides Mxenes,as a new kind of two-dimensional materials,have attracted the widespread attention in various fields because of their characteristic layered structures and excellent properties.Among them,titanium carbides,as a member of the Mxenes family,have also been deeply studied and applied in electrochemistry,photocatalysis and high-performance battery electrodes.In addtition,their research has been gradually developed in the field of nonlinear optics.Therefore,in this thesis,two kinds of titanium-carbides,Ti2C MXene and Ti3C2 MXene,were prepared to investigate the nonlinear optical properties.Moreover,in order to further improve the nonlinear optical response,the Fe3O4@Ti3C2 MXene hybrid material was prepared based on the layered structure of Ti3C2 MXene.A comprehensive understanding of the material was obtained through a variety of characterization methods covering surface morphology,microstructure and internal bonding state.The nonlinear optical absorption and nonlinear refraction of materials at discrete wavelengths were studied by the Z-scan technique,and the important optical parameters were obtained.Based on the good third-order nonlinear optical properties of the material,the wide band pulsed laser output was realized in the near-infrared ranging from 1 to 2μm.The content of this thesis is as follows:1.We briefly review the recent research progress of titanium carbides and introduce the preparation methods.Then the basic theory of nonlinear optical properties about the light interaction with the material is first interpreted.Next,the measurement principle and experimental method of the open/closed aperture Z-scan technique are introduced,and the key formulas are deduced.Finally,the Q-switching principle is discussed and the experimental setup is built.2.Ti2C MXene are prepared by selective etching with the hydrofluoric acid.The nonlinear optical properties of the sample are investigated at 1,1.3 and 2μm.The influence of excitation intensity on the nonlinear absorption behavior of the material is explored,and the corresponding nonlinear optical parameters are obtained.In order to observe the nonlinear optical behavior of materials under the strong incident intensity,the excitation irradiation is increased,then the two-photon absorption is observed,and the two-photon absorption coefficient is obtained.The nonlinear refraction of the material is also studied by the CA Z-scan experiments.Finally,in order to verify the saturable absorption properties of Ti2C MXene,the passively Q-switched lasers using it as a saturable absorber are demonstrated,and the shortest pulse durations obtained at 1,1.3 and 2μm are 128 ns,190 ns and 332 ns,respectively.3.The microstructure of the prepared Ti3C2 MXene is studied by various characterization methods,and the interlayer spacing is 0.89 nm.Then,the saturable absorption characteristics at 1～2μm are studied by using the open-aperture z-scan technology.Furthermore,we achieve the passive Q-switching operations at 1,1.3 and 2μm using Ti3C2 MXene saturable absorber.The shortest pulse width at at 1,1.3 and 2μm are 133 ns,297 ns and 337 ns,respectively.4.Given the layered structure of Ti3C2 MXene,Fe3O4 nanoparticles are used for the intercalation to the layered Ti3C2 MXene with the help of the ultrasound technology,in order to improve the nonlinear optical properties.We also characterize the hybrid materials with the typical TEM,SEM and Raman technology.Both the microstructure and internal chemical bond data show that Fe3O4 nanoparticles have been successfully inserted into the Ti3C2 MXene layers,which proves that we have effectively prepared the hybrid materials.Then the third-order nonlinear behavior in a wide band is studied by the z-scan technique.The modulation depth,saturation intensity,nonlinear absorption coefficient and nonlinear refractive index are obtained,which show that it has good saturable absorption characteristics.Finally,it is applied to realize the passive Q-switching operation.The output pulse widths at 1,1.3 and 2μm are 120,181 and 320ns,respectively.The experimental results confirm its potential in nonlinear optics applications.