Metamaterial Based On Superconducting Josephsen Plasma Oscillation

For a long time,the lack of efficient THz radiation sources has restricted the development of terahertz(THz)science and technology.The interlayer coupling of high temperature superconductors exhibits Josephsen junction behavior and can be used as a tunable THz radiation source.At present,the main problem of such sources is the low radiation power.In this paper,we study Josephsen plasma oscillations of Tl2Ba2CaCu2O8+x(TBCCO)thin films with metamaterial structure for increasing the coupling efficiency to fabricate new terahertz devices.The main research results are as follows:(1)Low-temperature THz time-domain spectroscopy(THz TDS)was used to measure the conductivity of TBCCO thin films,and a new calculation method was proposed to reduce the error of complex conductivity extraction caused by thickness error of the substrate.The penetration depth is calculated according to the complex conductivity,and the results are consistent with those obtained by other methods.(2)Josephsen plasma oscillation in HTS thin films is excited by the use of the metamaterial structure due to its field distribution structure and high quality factor.We designed and prepared superconducting metamaterials.Under the vertical incidence of THz wave,the resonance peak different from the structure itself was measured experimentally.Moreover,the frequency of the resonance peak was related to the temperature.This shows that Josephsen plasma oscillation is actually excited by metamaterials structure and coupled to free space.This provides a new way for us to construct a THz radiation source.