Studies On The Preparation And Third-order Nonlinear Optical Properties Of Black Phosphorus

In order to meet the development of optical communication technology,optical switch,laser technology and other fields,researchers have been looking for valuable materials to improve the performance of products.However,at present,the nonlinear optical materials can not keep up with the requirements of the rapid development of human beings.Therefore,it is urgent for researchers to explore new materials with good third-order nonlinear optical properties.This research is of great significance to promote the development of society.Black phosphorus is a new material which has attracted much attention in recent years.In the existing twodimensional materials,graphene has zero band gap,and transition metal sulfide has wide band gap,which is not enough to meet the needs of optoelectronic devices at present.Black phosphorus has a band gap between graphene and transition metal sulfides,which is necessary and useful supplement for 2D materials.To develop black phosphorus devices with high performance,high quality black phosphorus need to be prepared.In this thesis,the preparation of black phosphorus and the preliminary characterization of nonlinear properties were studied.The main contents of this paper can be summarized as follows:First,studies on the preparation of orthogonal black phosphorus crystal and its nonlinear optical properties.Black phosphorus crystals were obtained by vacuum sealed high temperature treatment with conversion from red phosphorus to black phosphorus.The black phosphorus crystals were characterized by X-ray diffraction,scanning electron microscope and energy dispersive X-ray spectroscopy.The results show that the prepared crystals are orthogonal black phosphorus.Single beam Z-scan method is used to measure the third-order nonlinear optical properties of orthogonal black phosphorus crystal,which shows good nonlinear saturable absorption effect.Second,studies on the preparation of black phosphorus quantum dots and their nonlinear optical properties.Black phosphorus quantum dots were obtained by liquid phase stripping of orthogonal black phosphorus crystals,and the dots sizes were controlled by the reaction time.The opening Z-scan curve of black phosphorus quantum dots with different sizes shows a centrosymmetric peak,which is mainly caused by saturated absorption.When measured at the same laser intensity,the peak intensity increases with the decrease of the size.Third,the preparation and nonlinear optical properties of black phosphorus by-product tetratin triphosphate.Tetratin triphosphate was prepared by mineralization method.The experimental results show that the substance has good nonlinear optical property.