Design aspects of Bi 2 Sr 2 CaCu 2 O 8+δ THz sources: optimization of thermal and radiative properties

[摘要] Impedance matching and heat management are important factors influencing the performance of terahertz sources. In this work weanalyze thermal and radiative properties of such devices based on mesa structures of a layered high-temperature superconductorBi2Sr2CaCu2O8+δ. Two types of devices are considered containing either a conventional large single crystal or a whisker. Weperform numerical simulations for various geometrical configurations and parameters and make a comparison with experimentaldata for the two types of devices. It is demonstrated that the structure and the geometry of both the superconductor and the electrodes play important roles. In crystal-based devices an overlap between the crystal and the electrode leads to appearance of a largeparasitic capacitance, which shunts terahertz emission and prevents impedance matching with open space. The overlap is avoided inwhisker-based devices. Furthermore, the whisker and the electrodes form a turnstile (crossed-dipole) antenna facilitating goodimpedance matching. This leads to more than an order of magnitude enhancement of the radiation power efficiency in whiskerbased, compared to crystal-based, devices. These results are in good agreement with presented experimental data.

[学科分类] 环境监测和分析

[关键词] high-temperature superconductivity;Josephson junctions;numericalmodelling;terahertz sources