Investigation Of Tunable Terahertz Transmission Based On Metamaterial

Terahertz wave is generally defined as electromagnetic wave from 0.1-10 THz,which has great potential value but not been effectively developed. It is a key step to realize active control in the terahertz technology process. Currently, most of methods used to achieve active control of terahertz wave are highly dependent on the non-linear properties of the material itself, leading to a small tuning range of terahertz wave. Based on the difference of thermal expansion coefficient between bi-layer materials, the thesis designed a three-dimensional deformation structure to realize a dynamic tunable terahertz filter. The main contents are listed as following:(1) Combining the conventional split-ring resonator(SRR) with flexible cantilever, we designed double(Al and Si O2) flexible cantilever arrays. Utilizing the difference of thermal expansion coefficient between the two-layer materials, we obtained bending cantilevers by varying the temperatures, thus designing a tunable filter with a tuning range of 0.32 THz. The thesis also deeply analyzed the physical mechanism of the structure.(2) The thesis also used the shape memory materials(SME) Ni Ti alloy to design and simulate the double SRR flexible cantilever arrays, theoretically verified the feasibility of the Ni Ti shape memory alloy in metamaterial design. Shape memory effect means that the material is deformed under specific conditions, by applying an appropriate external conditions, the material can be restored to the original shape.Compared with ordinary metals, shape memory alloy possesses larger deformation,stronger recoverability and practicability.(3) In order to verify the shape memory effect of Ni Ti, we fabricated the SRR flexible cantilever arrays basing on the conventional photolithographic techniques.Using the interferometer, we verified the shape memory effect of Ni Ti alloy and obtained good recoverable effect.(4) Using terahertz time-domain spectroscopy system(THz-TDS), we measured the transmission spectra of the sample at different temperatures. The thesis deeply analyzed the reasons which leaded to the difference between the simulation and experimental results and also put forward the further optimized plan.