Research On Efficient Visualization Of Terahertz Detector

Terahertz(THz)technology has great research value and broad application prospects in the fields of object imaging,environmental monitoring,biomedicine,high-speed space communications,and national security because of the unique properties of THz wave.As the core device in the THz field,THz detector has achieved significant results in recent years,but it still faces the challenge of economic,practical and efficient detection.Therefore,the development of new THz detectors,especially visual detection,has attracted more and more attention.Temperature-sensitive cholesteric liquid crystal has become one of the key research directions of THz detection technology in recent years since it has unique thermochromic properties which can show THz power in visible color form,and has mature industrial technology foundation.However,the current THz detectors based on cholesteric liquid crystals has low absorption efficiency for THz wave and under macroscopic color changes for visual detection,resulting in poor detection sensitivity.In order to solve the above problems,a new type of visual THz power detector with excellent performance is designed and implemented in this paper.The main content of the dissertation is divided into three parts:1.We discuss the basic characteristics and preparation methods of three-dimensional porous graphene(3DPG)firstly and characterizes its internal porous structure and intrinsic information.It focuses on the THz absorption properties of 3DPG and one whose overall absorption rate in frequency range of 0.5-1.5 THz is up to 97%has been achieved.And its absorption characteristics can be maintained prefectly even under the oblique incidence of THz wave.2.The microencapsulation of cholesteric liquid crystal is discussed,as well as a temperature sensitive cholesteric liquid crystal capsule(CLCM)with unique omni-directional reflection characteristics and thermochromic effect.A micro-temperature measurement platform is built to study the steady-state and transient temperature changes of 3DPG,which confirms its excellent thermal conductivity.3.A new type of visual THz power detector is designed and realized by combining CLCM and3DPG.The sample preparation,experimental setup and sample testing are analyzed systematically to study the steady-state THz power is visually and quantitatively.The detection intensity of THz is up to 2.77x10~2 m W/cm~2.And its lowest detection power is only 0.009 m W.Further research shows that,compared with the nonlinear relationship between Hue value and THz power of single CLCM,Hue value of multiple CLCMs change linearly with THz detection power.An automatic recognition method based on artificial intelligence is designed to simplify the data analysis and process of CLCM visual detection of THz wave.The visual detector can be used in THz system alignment,THz wave beam analysis,THz imaging and sensing.