Theoretical study on optimization of THz-wave emission device using Josephson junction of high-temperature superconductors

点击翻译按钮获取中文摘要

Electromagnetic wave with frequency around 1 THz is expected to have a wide range of applications in biological and medical fields. Although it has been difficult to generate such stable electromagnetic wave with conventional electric or optical devices, stable emission of such wave became possible recently using intrinsic Josephson junctions of high-Tc superconductors. I investigated emission properties of such devices by large-scale numerical simulations of an established theoretical model and found that the surface impedance Z is crucial. Without magnetic fields emission becomes maximum when the bias current corresponding to the cavity resonance is applied, and the optimal emission is obtained around Z=50 for the fundamental mode. When magnetic fields along junctions are applied, emission intensity takes a maximum value at zero field and monotonically decreases as the field increases for Z>50, while it takes a maximum value for a small but finite magnetic field for Z<50.