Towards practical applications of THz Josephson oscillators with sub-mW power and 500 GHz frequency tunability

Using a double-sided fabrication method, we fabricated Bi₂Sr₂CaCu₂O₈ (BSCCO) intrinsic Josephson junctions (IJJs) with a gold-BSCCO-gold structure. Coherent emission is observed at large dc input power, where a hot spot and “cold” part of the stack, coexist. The power, directly detected with a bolometer, is as high as 25 μW, implying the integrated power should be already in the order of sub-mW. We have successfully pumped a Nb-based Josephson junction and a grain boundary Josephson junction. Also with a wide tunable frequency range, BSCCO THz emitters will find themselves many practical applications, e.g., local oscillators of SIS, HEB, and Josephson mixers.