Operation With Terahertz Mixer Based on YBaCuO Josephson Junction: Analysis and Numerical Simulation

This article presents theoretical analysis and modeling of YBaCuO superconducting Josephson mixer for terahertz frequency band. The study was carried out both for the mixing at the first harmonic and for the case of high harmonic mixing. The numerical solution based on resistively shunted junction model was obtained for the YBaCuO junction with typical experimental parameters. Optimizing mixer performance included choosing the proper operating point and the local oscillator power. A study on the effect of RF input power, frequency, and the harmonic number on conversion efficiency was carried out. The theoretical predictions presented in the work provide a simple method for optimal control of the Josephson mixer and demonstrate good qualitative agreement with direct modeling. For the first time, the optimum of the conversion efficiency versus signal frequency was analytically obtained.