  By performing three-dimensional (3D) simulations that demonstrate the
neutrino-driven core-collapse supernovae aided by the standing accretion shock
instability (SASI), we study how the spiral modes of the SASI can have impacts
on the properties of the gravitational-wave (GW) emission. To see the effects
of rotation in the non-linear postbounce phase, we give a uniform rotation on
the flow advecting from the outer boundary of the iron core, whose specific
angular momentum is assumed to agree with recent stellar evolution models. We
compute fifteen 3D models in which the initial angular momentum as well as the
input neutrino luminosities from the protoneutron star are changed in a
systematic manner. By performing a ray-tracing analysis, we accurately estimate
the GW amplitudes generated by anisotropic neutrino emission. Our results show
that the gravitational waveforms from neutrinos in models that include rotation
exhibit a common feature otherwise they vary much more stochastically in the
absence of rotation. The breaking of the stochasticity stems from the excess of
the neutrino emission parallel to the spin axis. This is because the
compression of matter is more enhanced in the vicinity of the equatorial plane
due to the growth of the spiral SASI modes, leading to the formation of spiral
flows circulating around the spin axis with higher temperatures. We point out
that a recently proposed future space interferometers like Fabry-Perot type
DECIGO would permit detection of these signals for a Galactic supernova.
