Electromagnetic field analysis of coherent terahertz radiation emitted from stacks of intrinsic Josephson junctions of BSCCO with microstrip antennas*

The observation of coherent terahertz radiation from a stack of intrinsic Josephson junctions (IJJs) in Bi₂Sr₂CaCu₂O_8+δ (BSCCO) highlighted the potential of using high-T_c superconductors as compact and convenient terahertz sources. So far, synchronized IJJ mesa arrays were demonstrated to produce the output power up to 0.6 mW [Benseman et al., APL (2013)], which is presently the highest recorded level among all available terahertz sources. To increase the output power further up to milliwatt-level, we need to mitigate impedance mismatch at the boundary between an emitting IJJ stack and a dielectric medium or free space. In this study, we implement the electromagnetic field analysis of the radiation emitted from IJJs stacks with microstrip antennas, which are designed for highly efficient radiation. We established a microfabrication process based on the lift-off technique to pattern the microstrip antenna. In this talk, we will discuss the characteristic radiation behavior associated with the bath and local temperatures and variation in polarization characteristics depending on the bias point.