  We study the Terahertz (THz) emission mechanism in BSCCO with an external
magnetic field theoretically. The total power is proportional to the square of
the number of layers and the frequency. Under the small size limitation, the
angular distribution is similar to that in the dipole emission. The present
theoretical results for THz power output are in the same order of magnitude as
the experimental ones, in contrast with previous simulations. A series of
size-dependent intrinsic frequencies are also observed. When the external
frequency induced by the external current resonates with intrinsic ones, the
distinct THz emission is observed.
