  Understanding gravitational wave emission from core-collapse supernovae will
be essential for their detection with current and future gravitational wave
detectors. This requires a sample of waveforms from modern 3D supernova
simulations reaching well into the explosion phase, where gravitational wave
emission is expected to peak. However, recent waveforms from 3D simulations
with multi-group neutrino transport do not reach far into the explosion phase,
and some are still obtained from non-exploding models. We therefore calculate
waveforms up to 0.9\,s after bounce using the neutrino hydrodynamics code
\textsc{CoCoNuT-FMT}. We consider two models with low and normal explosion
energy, namely explosions of an ultra-stripped progenitor with an initial
helium star mass of $3.5\,M_{\odot}$, and of an $18\,M_{\odot}$ single star.
Both models show gravitational wave emission from the excitation of surface
g-modes in the proto-neutron star with frequencies between
$\mathord{\sim}800\,\mathrm{Hz}$ and 1000\,Hz at peak emission. The peak
amplitudes are about $6\, \mathrm{cm}$ and $10\, \mathrm{cm}$, respectively,
which is somewhat higher than in most recent 3D models of the pre-explosion or
early explosion phase. Using a Bayesian analysis, we determine the maximum
detection distances for our models in simulated Advanced LIGO, Advanced Virgo,
and Einstein Telescope design sensitivity noise. The more energetic $18
M_\odot$ explosion will be detectable to about $17.5 \,\mathrm{kpc}$ by the
LIGO/Virgo network and to about $180\, \mathrm{kpc}$ with the Einstein
Telescope.
