Terahertz Transmission And Absorption Characteristics Of The Resonant Ring Of Metal

In this thesis, terahertz transmission properties through structures of split ring resonance (SRR) are investigated in the far field using THz time-domain spectroscopy system (THz-TDS). We discuss the phenomena of resonant transmission and absorption experimentally, and analyze the factors that affect the frequency of the resonant transmission peak.Free charge in metal rings occurs directional moving with effects of electric and magnetic fields when terahertz wave is incident in split ring (SR). It makes transmission and absorption peaks at certain frequencies by electric and magnetic responses between metal rings. There is another kind of absorption which is made by its structure at natural frequency of SR. In this letter, transmitted and absorbed properties of SR structures are discussed, which are impacted by terahertz wave. Our specific works are as follows: (1) do the research of different transmission mode by changing direction of split; (2) do the research by changing angles of terahertz electric wave vector with split of SR; (3) do the research by changing angles of terahertz magnetic wave vector with split of SR; (4) Research the influence of substrate with exciting light. Our conclusion contains: (1) SRR structure has anisotropic property. The directions of split will decide transmission mode of terahertz in samples. (2) Different modes of dipole oscillating are made by changing electric wave vector, and its absorption is also affected. However, natural frequency of SRR is decided by lattice size, independent of transmission mode. (3) Magnetic response occurs when magnetic wave vector has component which is normal to sample surface. It makes phenomenon of absorption more apparently. In addition, decreasing component of which is parallel to sample surface can make transmission peak move to low frequency. (4) The resonance property of split rings is weakened by effect of exciting light, and the carrier density of semiconductor decided its sensitivity to exciting light.Innovation of this letter is as follows: According to results of SRR structure, the transmission energy is moving by changing electric wave vector of which is vertical to the direction of split in SRR, and we have done some theoretical analysis; changing magnetic wave vector can make different frequencies of transmission peaks.Infections to resonance properties of SRR by terahertz electric and magnetic wave vectors are discussed in this letter. It can be a reference for researching terahertz devices.