Research On Modulation Of Terahertz Wave Based On Ferroelectric Materials And Metasurfaces

Terahertz modulators are important terahertz devices.Ferroelectric materials provide new choices for terahertz functional devices,as their dielectric properties could be tuned by optical or electric fields.In addition,metamaterial has also been used in terahertz devices due to its unique optical properties,which promotes the development of terahertz technology.In this paper,the dielectric properties of silicon-based BTO and STO ferroelectric thin films were investigated in terahertz range.Furthermore,the modulation of terahertz waves based on silicon-based metasurface are studied.The main results of the researches are as follows:(1)The preparation process of silicon-based BTO film is introduced.The complex permittivity of the BTO film under external optical powers was calculated.The experimental results showed that when the optical power is tuned from 0 mW to 450 mW,the real part of the dielectric constant for BTO film can be up to 74%.(2)The transmission modulation of the silicon-based BTO,STO single-layer film and BTO/STO multilayer film are compared when they are under the effect of the same optical field.The experimental results show that the transmittance of the three films were decreased with the increase of the external optical powers,and the modulation could reached to 29.12%,14.03% and 28.43%,respectively.(3)An active multifunctional terahertz modulator based on plasmon-induced transparency(PIT)metasurface under the effect of external infrared light was investigated theoretically and experimentally.A distinct transparency window resulting from the near field coupling between two resonators could be observed in the transmission spectra.Experimental results showed a phenomenon infrared light induced blue shift on the both resonances with increasing optical powers.