The Study Of The Nonlinear Optical Property Of MoS₂ Nanosheets In The Polymer Matrix Composite Film

Transition metal sulfides have attracted much attention because of their unique physical and chemical properties.Because of its special band structure,optical response and electron transport properties,two-dimensional MoS₂ material become a new physics and material science research hotspots.Compared to graphene with zero band gap,the two-dimensional structure of MoS₂ with tunable band gap has important application value in optoelectronic devices.Recent studies have found that single layer MoS₂ nanosheets synthesized by the hydrothermal exfoliation method from the material of molybdenum disulfide?MoS₂?has excellent nonlinear optical properties.For example,the study found that single MoS₂ nanosheets under the irradiation of femtosecond laser,have very strong two-photon absorption effect,thus the ultrafast nonlinear properties imply a huge potential of the single layer MoS₂ nanosheets semiconductors in the development of optoelectronic devices,such as the laser protection,nonlinear modulator,etc.In this paper,we firstly prepared good performance of single-layer MoS₂ nanosheets by hydrothermal exfoliation method.As is known to all,MoS₂ has a special sandwich structxure,the upper and lower two layers of inert sulfur atoms wrapped in a middle layer between the molybdenum atoms,and there is weak Fan Dehua force between the layers.Under normal circumstances,the exfoliation good in the dispersion occurs in irreversible agglomeration and sedimentation.However,we put the organic functional groups on the surface of MoS₂ by chemical monolithic method,which will increase the distance between each layer,and the nanosheets is no longer easy to gather.Then,these MoS₂ nanosheets are incorporated into a variety of polymer material,such as polymethyl methacrylate?PMMA?,including polyurethane?PU?and polyimide?PI?.After preparation of the MoS₂-organic composite film such as PMMA-MoS₂,PU-MoS₂ and PI-MoS₂ composite film,and we studied the effects of different MoS₂ concentration on the incorporation of control properties of light limiting effect.The experimental results show that the MoS₂ composite has good optical limiting properties and continuous tunable properties in the long wavelength range and large range of laser intensity.As a convenient and sensitive measurement method,Z-scan experimental setup can effectively represent the three order nonlinear processes in materials.We constructed a Z-scan nonlinear optical measurement system based on femtosecond laser pumping,and fully debugged it.Then we systematically studied the three order nonlinear absorption properties in the PMMA-MoS₂ and PU-MoS₂ composite organic material thin film material by Z-scan method,trying to find out the possible saturable absorption?SA?and reverse saturable absorption?RSA?physical process in composite.According to the measured results of open aperture Z-scan,we obtained the nonlinear optical correlation data for these two organic composite films.At the same time,we studied the nonlinear effects of materials under different laser intensities at 532 nm?nanosecond?and 800 nm?femtosecond?laser pulses in detail.More significant is that the elastic mechanical properties of organic thin films is helpful to design scalable nonlinear optical devices,we studied the tensile properties and the corresponding linear and nonlinear optical properties of the MoS₂-organic composite film,and then discussed the optical uniform performance of our sample and the ability of laser damage resistance of our design features organic composite materials.