Research On Broadband Terahertz Absorbing Materials Based On Three-dimensional Graphene

In recent years,scientific research institutions of major world countries have increased their research efforts in the terahertz technology field.This is because the terahertz band is not only very important in the future of wireless communication bands,but also has a wide range of applications in security imaging,product quality inspection,human health monitoring and so on.With the increasing demand for terahertz waves in wireless communication,imaging radar,anti-terrorism security and other fields,the development of terahertz absorption and shielding materials has received more and more attention.Terahertz absorption materials can not only improve the signal-to-noise ratio of the application system,optimize the imaging and communication quality,but also reduce the impact of complex electromagnetic waves on the human body,and also give the relevant system stealth performance and so on.In recent years,research on terahertz absorbing materials with broadband and high absorption characteristics has become one of the research hotspots in the terahertz field.Under this background,the research work of broadband,high absorption and flexible terahertz absorbing materials based on three-dimensional graphene is carried out.The main results are as follows:The work of this thesis first studied a stretchable terahertz wave absorbing material based on three-dimensional graphene.Based on the structure of three-dimensional graphene,we combined with polydimethylsiloxane(PDMS)to produce a flexible,stretchable,wearable terahertz absorption device.THz-TDS time-domain spectroscopy system was used to test the transmission function of three-dimensional graphene foam/PDMS(polydimethylsiloxane)composite materials to terahertz waves.The reflection function of three-dimensional graphene foam/PDMS(polydimethylsiloxane)composite materials to terahertz waves was tested using a laser pump system.Comprehensive analysis of the reflection and transmission of the three-dimensional graphene foam/PDMS(polydimethylsiloxane)composite material to the terahertz wave,so as to obtain the absorption function of the composite material to the terahertz wave,the test results show that the composite material has up to 92% terahertz wave absorption rate,and at 30° angle of incidence and 40% stretch,it has good absorption characteristics.Shows very good comprehensive absorption performance.Then two types of terahertz wave absorbing materials with pore gradient structure based on three-dimensional graphene are introduced,and the preparation process of the two terahertz wave absorbing materials is introduced in detail.Absorption properties of terahertz waves.Finally,this paper studies a composite material combining three-dimensional graphene and graphene powder,details the preparation process of graphene powder,and explores the enhancement effect of this material on terahertz wave absorption.The transmittance and reflectivity of this composite material to terahertz waves were tested by THz-TDS system and laser pump system respectively.Using an angle rotator,the absorption function of terahertz waves by three-dimensional graphene foam/graphene powder composite materials under different incident angles was tested.