Extensible approach to nonlinear circuit simulation of terahertz radiation phenomena from stacked Josephson junctions

Abstract This paper proposes an enhanced numerical simulation of a high-Tc cuprate terahertz source using the LTspice® electric circuit simulator. By implementing a nonlinear circuit model proposed in our previous work utilizing behavioral sources in LTspice, we accurately reproduce current–voltage-radiation power characteristics of the device measured by the authors over the entire bias points. We also identify that high-frequency losses significantly increase the damping of the oscillation in the gauge-invariant phase differences of stacked Josephson junctions. This model enables quantitative analysis of maximum radiation intensity through structural optimization, paving the way for a systematic approach to efficient device design.