Research Of Terahertz Functional Device Based On Metamaterial

Terahertz(THz)wave refers to electromagnetic wave whose frequency ranges from 0.1 THz to 10 THz.THz wave is at a special position of electromagnetic spectrum.It not only has features related to electronics and photonics,but also has some unique properties such as low photon energy,multifunctional spectrum and selective high transmission.Terahertz waves have developed rapidly in recent years.Metamaterials,known as “artificial atoms” or “singular medium”,also developed rapidly in recent years.The rapid development has led to the emergence of metamaterial based terahertz devices.In this thesis,a metamaterial structure is designed by combining the classical double spilt ring and metal strip dipole structure.A passive terahertz band-stop filter and an active modulator were realized using the strcture.Simulation software CST Microwave Studio was used to obtain the optimal structure parameters.The functional devices were fabricated by microfabrication,and characterized by THz-TDS,OPTP and dynamic modulation systems.The passive filter realize a band-stop filter with bandwidth of 0.3THz and tunable central frequency by varying the geometric parameters.LC equivalent circuit were used to help design and determine the resonance frequency.The active terahertz modulation is characterized by THz-TDS and dynamic modulation system.Significant terahertz modulation was obtained when appropriately excitated.Optical and electrical signal both have good modulation effect.The optical modulation depth can be varied by the loading voltage of the device.The OPTP test shows that the loading voltage of the device can significantly vary the photogenic carrier concentration of the material.For electrical modulation,the device will modulate the terahertz wave under a certain voltage loading mode.The modulation mechanism were explained using energy band theory.The voltage modulation rate is 30 KHz,which is higher than silicon-based optical terahertz modulator.