Study On Third-order Nonlinear Optical Properties Of Graphene And MoS₂ Composite Materials

Since the discovery of nonlinear optical properties in some materials,materials with nonlinear optical properties have broad application value in many fields,such as optical switches,optical communications,optical communications,optical data storage,and so on.Materials with excellent non-linear optical properties have the characteristics of low optical loss,relatively large nonlinear coefficient,and good nonlinear optical effects.With the rapid development of the laser industry the non-linear performance requirements of precision optical instruments for optical materials are also increasing.Therefore,exploring excellent nonlinear optical materials has become an important research direction for current researchers.The dual electrical and optical properties of semiconductor materials have broad application prospects in the field of optoelectronic devices and functional materials.However,due to the small size and poor dispersion and stability of semiconductor materials they need to be compounded with other materials to enhance the relevant physical and chemical properties of the materials.Generally,composite materials can effectively suppress the agglomeration between semiconductor materials,help to improve the dispersion of semiconductor materials,and can effectively improve the nonlinear optical properties of the materials.If the composite materials have similar nonlinear effects,the synergistic effect between the two materials will increase the third-order nonlinear optical effect of the composite materials.Graphene and MoS₂ are typical two-dimensional semiconductor materials,and both have good nonlinear optical effects.Graphene has a stable and orderly two-dimensional plane structure,large specific surface area and ultra-fast electron transfer speed,which can be used as a support material for composite materials.Its stable and ordered structure can make the semiconductor material compound with it and improve the stability of material,;its large specific surface area can effectively prevent the semiconductor materials from agglomeration and improve the dispersion of the material;its ultra-fast electron transfer speed can improve the third-order nonlinear characteristics of the composite material.Therefore,using graphene as the substrate,combining grapheme with semiconductor materials can effectively improve the performance of semiconductor materials,and the composite is expected to become a good optoelectronic device materials.The main research content of this article is as follows:The first chapter the theory of nonlinear optics,the research and development of nonlinear optical materials,the method of measuring third-order nonlinear effect,and the advantages and calculation methods of Z-scan.The second chapter gives a brief overview of MoS₂,and the MoS₂ is prepared by hydrothermal reaction.Then change the reaction time and reaction temperature to prepare MoS₂ produced under different reaction conditions.Finally,the structure and morphology characterizations of MoS₂ were characterized and the third-order nonlinear optical properties were studied.It was found that MoS₂ has a saturated absorption characteristics and a positive nonlinear refractive indexChapter 3 introduces that Graphene Oxide（Go）prepared by the modified Hummers method,and rGO/MoS₂ prepared by hydrothermal.The structure and morphology characterizations of rGo/MoS₂ were characterized,and their third-order nonlinear optical properties were studied.Through Z-scan data,it is found that both graphene oxide and composite materials exhibit saturated absorption characteristics and positive nonlinear refractive index.The third-order nonlinear optical properties of the composite material calculated by the nonlinear theoretical formula are better than those of the pure sample of MoS₂ and grapheme,indicating that the composite material of rGO/MoS₂ has more excellent nonlinear optical properties.Chapter 4 provides a brief summary of the work done in this paper,as well as plans and prospects for the next step.