Terahertz wave emission and phase motion in intrinsic Josephson junctions

Since the observation of the terahertz wave emission from the intrinsic Josephson junction of Bi2Sr2Ca-Cu2O8, there have been a lot of arguments on properties of emitted electromagnetic waves. The difficulty in the theoretical analysis to identify the relation between the phase motion and emitted waves lies in the fact that there are more than hundred-times different length scales, the Josephson vortex size and wavelength of terahertz waves. We investigate, by numerical simulation, the relation between emitted electromagnetic waves and phase motions by use of a reduced model where the system of the junctions is approximated by the periodic system and couples to the electromagnetic fields in the vacuum with a large length scale. Due to the oscillatory Josephson current, the emitted wave shows a similar pattern as the dipole emission. (C) 2010 Elsevier B.V. All rights reserved.