THz Wave emission from the intrinsic Josephson junctions of high T _c superconductors

Relating to the recent observation of a THz wave emission from the intrinsic Josephson junction of Bi-2212, we investigate temporal and spatial behaviors of electromagnetic fields around the junctions by numerical simulation. We consider 1)xz-model, where junctions and leads are stacked in the z-direction with homogeneity in the y-direction, and 2)xy-model, where junctions have a rectangular shape in the xy-plane with homogeneity in the z-direction. The result of the xz-model shows that the emitted electromagnetic field has the spatial pattern similar to that of the dipole emission. The result of the xy-model shows that waves are emitted in the all directions of the xy-plane and the frequency of the oscillation is controlled by the shorter length and is given by the Josephson frequency. The voltage-dependence and the angle-dependence of the emitted power are also studied.