Research On High Performance Terahertz Filters Based On Compact Array

The terahertz band is between the millimeter wave and infrared wave,and has many characteristics that the microwave and the optical wave do not have,such as transientity,safety,penetration and wide band property.Hence,terahertz technology can widely used in terahertz imaging,terahertz time-domain spectroscopy,anti-stealth radar,terahertz communication and many other fields.At present,the research on terahertz sources and detectors has been developed rapidly.However,the lack of terahertz devices with good performance has hindered the practical application of terahertz technology.As an important modulation frequency selection option,the terahertz filter has great contribution to the performance of the terahertz system.Terahertz filters with properties like angle insensitivity,polarization independence,tunable,multi-frequency filtering has become one of the research hotspots of terahertz devices.This paper conducts in-depth theoretical research on the urgently needed filters with excellent performance in the terahertz system.Starting from the basic model,by optimizing the filter structure,materials,and size parameters,two excellent terahertz filters are designed.The main work completed by the thesis is as follows:(1)A design method for compact arrays is proposed.Based on the compact arrays,a cross-shaped broadband terahertz band-stop filter with angle-insensitive and polarization-independent are designed.By adjusting the parameters such as arm length,line width,substrate size,and structural unit period,the performance of the terahertz band-stop filter is optimized.The filter has 750 GHz 10d B bandwidth;its cutting edges are 258 d B/THz and 180 d B/THz;the depth of the filter at the resonance point reaches48 d B.Meanwhile,the proposed filter is independent of the electric field polarization direction and it's also insensitivity to the incidence angle in a large range.Compared with the traditional design,the bandwidth of the filter based on the compact array is increased by 220 GHz,the slope of the rising and falling edges is increased by 235% and200%,and the stop-band attenuation is increased by 20 d B.The compact array can effectively increase the effective receiving area of the filter for electromagnetic waves,and by introducing spatial asymmetry,it can excite an additional antisymmetric resonance modes which widen the filter working band and optimize the frequency selection capability.Through the use of compact array design on a variety of common structures,the effectiveness of the compact array design method is also verified.(2)Based on the method of combining resonators,a dual-band boradband terahertz bandpass filter is proposed.By integrating a cross-shaped resonator and a concentric square resonator on one frequency selective surface,the filter has excellent performance of filtering in multiple frequency bands.By adjusting the structural size parameters of the filter,its performance has been optimized.The filter has two passbands with bandwidths of 120 GHz and 478 GHz,and has four sharp edges.The rising and falling edge slopes are 57 d B/THz,514 d B/THz,242 d B/THz,298 d B/THz,respectively.The filter also has stable gain performance in the passbands.By combining the component resonators organically,compared with current multi-frequency terahertz filters with bandwidth less than 200 GHz and edge slope less than 200 d B/THz,the performance of proposed filter is more superior.