Study On Electrode And Substrate Of Terahertz Photoconductive Antenna

Due to the terahertz electromagnetic wave has unique properties such as safety and high transmission,it has great research value and broad application prospects in the fields of nondestructive examination,medical imaging,and wireless communication.As one of the most important terahertz radiation sources,the terahertz photoconductive antenna has attracted extensive attention because of its simple structure and high radiation power.Through the in-depth study of photoconductive antenna,improving terahertz radiation power and reducing excitation cost are the main difficulties in the practical process of photoconductive antenna.Combined with the current research status of photoconductive antenna,this paper has carried out some innovative research on the electrodes and photoconductive materials that affect its emission performance.Firstly,this paper systematically introduces the radiation characteristics and application fields of terahertz electromagnetic wave,reviews the research status of the photoconductive antenna at home and abroad,analyzes the mechanism and theory of terahertz electromagnetic wave generated by a photoconductive antenna with different aperture,and summarizes the main problems of photoconductive antenna,which lays a foundation for the research of this paper.The main work and innovations of this paper are as follows:1.A new type of photoconductive antenna electrode embedded interdigital electrode is proposed.The model of the terahertz photoconductive antenna is established by using the simulation software based on the finite element method,and the influence of the electrode on the transient photocurrent of the photoconductive antenna is studied.The simulation results show that the transient photocurrent peak generated by the embedded interdigital electrode photoconductive antenna can reach 5.5 times that of the traditional linear photoconductive antenna,and the current peak increases gradually with the increase of electrode embedding depth.The advantage of the electrode is that it can not only enhance the collection of substrate carriers but also reduce the reflection of the electrode to the incident laser and enhance the absorption of the substrate to the laser.Compared with other electrodes,embedded interdigital electrode has the advantages of simple structure,low fabrication difficulty,and good reinforcement.At the same time,the embedded electrode structure is expected to be extended to other geometry electrodes,which provides a valuable reference for researchers to develop new antenna electrodes.2.Aiming at the problem of the high excitation cost of terahertz photoconductive antenna,a new photoconductive material In P basedGaAs / In As superlattice grown at low temperature is developed.During the preparation of the material,the main factors affecting its appearance were analyzed.The material can not only be excited by a 1550 nm fiber femtosecond laser but also effectively improve carrier mobility and resistivity and reduce carrier lifetime.Therefore,using the photoconductive material as the photoconductive antenna substrate can greatly reduce the excitation cost of the photoconductive antenna and produce high-power terahertz electromagnetic waves.In conclusion,the photoconductive material is conducive to promoting the development of the terahertz photoconductive antenna and accelerating its practical process.