Research On Terahertz Wave Devices Based On Two-dimensional Photonic Crystals

With the rapid development of 5G communication technology and computer technology,the requirements of information transmission and processing in the context of big data information and intelligent construction are greatly improved.In the face of the continuous development of wireless communication demand and technology,spectrum resources are increasingly scarce.It is necessary to continuously develop new spectrum resources to improve the information transmission rate.Terahertz wave occupies the ultra wide spectrum of 0.1-10 THz band,and terahertz communication has the advantages of large transmission capacity,high security,good penetration,so it has great development potential and application prospects.Terahertz technology has gradually become an important direction of the development of the new generation of wireless communication industry.The development of terahertz wave communication is inseparable from terahertz wave functional devices.The development of terahertz beam splitter and terahertz wave 4-2 encoder drives the improvement and progress of terahertz communication system,which is also an indispensable and crucial part of terahertz communication system.Based on the characteristics of photonic crystal,the terahertz beam splitter and terahertz 4-2 encoder are studied in this paper.The specific work is as follows:(1)Based on the band gap and local properties of photonic crystals,a terahertz beam splitter with fixed splitting ratio and an optically controlled terahertz beam splitter with adjustable splitting ratio are proposed.Using Rsoft software,combined with the plane wave expansion method(PWE)and the finite difference time domain method(FDTD),the simulation analysis and performance research of two kinds of terahertz beam splitters are carried out.The results show that: the transmittance of two output ports is 49.889%,the total transmittance is 99.778%,and the additional loss is 0.009dB for the terahertz beam splitter based on photonic crystal with fixed splitting ratio;an optically controlled terahertz beam splitter based on photonic crystal with adjustable splitting ratio can be adjusted in the range of 0.08?1.29,the total transmittance is more than 98.5%,and the additional loss is less than 0.066dB.(2)Based on the band gap and local properties of photonic crystal,a terahertz 4-2 encoder based on photonic crystal is proposed.The proposed terahertz 4-2 encoder is simulated and analyzed by using Rsoft software,combined with the plane wave expansion method(PWE)and the finite difference time domain method(FDTD).The results show that the size of the terahertz wave4-2 encoder based on photonic crystal is only 5.499mm×4.797 mm by reasonably designing the length of the waveguide and the position of the dielectric column,which can realize the logic coding function of the terahertz wave 4-2 encoder in the wavelength range of 251?m ? 252?m,the contrast varies from 13.27 d B to 18.02dB,and the response time is not less than 167ps.The proposed terahertz beam splitter and terahertz wave 4-2 encoder have the advantages of small size,low loss,short response time and easy integration,which will have a broad application prospect in the future terahertz wave communication.