Numerical simulations of THz emission from intrinsic Josephson junctions

Recently, a strong coherent THz wave emission was observed in the mesa-shaped intrinsic Josephson junction of Bi-2212 with a constant bias current and without any applied magnetic field. We investigate the size-effect of the THz wave emission by use of the numerical simulation. We assume in-phase motions, and the equations for junctions, leads and the vacuum are solved simultaneously in two-dimensional models. The emitted wave has a similar pattern as in the dipole emission, and electromagnetic oscillations inside the two-dimensional junction show creation and annihilation of flux loops, which are quite different patterns from ones in a one-dimensional junction.