Research And Design On Terahertz-band Modulator Based On Metamaterials

This paper is mainly based on electromagnetic properties of Metamaterials to complete work in three parts: polarization insensitive Terahertz modulator design of electromagnetically induced transparency effects,the design and development of multi-band modulator,ultra wide-band adjustable absorber based on low conductivity materials design.EIT effect of THz modulator design completed the following three main parts of the work: First,the bright-bright mode coupling electromagnetically induced transparency effect of polarization insensitive THz modulator transparency was designed,which it's peak frequency is 0.828 THz and Q value is 15.3.we achieved two kinds of modulation mode,which the modulation depths of transparency peak amplitude are respectively 73% and 34%,through altering substrate conductivity by means of laser light irradiating semiconguctor substrate;Secondly,the bright-bright mode coupling EIT effect of polarization insensitive THz modulator was designed,which it's transparency peak frequency is 0.3 THz and it's Q value is 150.Finally,Through studying the complementary structures of both devices found that complementary principle is not valid inside the band of e EIT effects.In the design and manufacture of multi-band modulator mainly have completed the four parts of the work : First,a type of dual-band resonant structure of a loaded spiral arm structure was designed.The resonant frequency of the first resonant structure are respectively 0.28 THz and 0.59 THz.Using laser irradiation to design two modulation methods: modulation depth for S21 amplitude of the first resonant point is 54.8% and modulation depths for S21 amplitude of both resonant points are 54.8%;Secondly,on the basis of the first dual-band resonant structures added an L-shaped metal structure to implement a three-band resonant structures,the resonant frequency points are respectively 0.256 THz,0.49 THz and 0.67 THz;Using laser irradiation to the tri-band resonant structure to achieve resonance of amplitude modulation.Respectively,for the second and third resonant frequencies to achieve S21 amplitude modulation,each of these modulation depths are 54.8%.Three resonant frequency points of modulation,of which each modulation depths is 50%,have been achieved at the same time.Finally,physical material processing and testing was completed,testing and simulation results coincide.In the design of ultra wide-band adjustable absorber which based on low conductivity materials mainly have completed the four parts of the work: first,lowconductivity materials of ultra wide-band adjustable absorber based on split ring was designed.Half peak absorption bandwidth is 4 THz,and fractional bandwidth is 108%.By laser irradiation to the Silicon semiconductor that embedded structure,half-peak absorption bandwidth which respect to x-polarized waves achieved dynamic modulation that the modulation range is from 2.4 TH to 3.8 THz.Second,a symmertrical composite structure,which half of bandwidth is 4.3 THz,was achieved using split ring structure,and fractional bandwidth is 118%.By laser irradiation to the Silicon semiconductor that embedded structure,half-peak absorption bandwidth which respect to arbitrarypolarized waves achieved dynamic modulation that the modulation range is from 1.7TH to 4.1 THz.