  Stability domains (i.e. pump frequency detuning range) of a single dark
soliton (or platicon) and dark breather in high-Q Kerr optical microresonators
with normal group velocity dispersion is studied for a wide range of pump
amplitudes within the framework of the Lugiato-Lefever model. The effect of the
significant fragmentation of the stability domains at high pump intensities is
revealed. The existence of stable drifting dark solitons (platicons) is
demonstrated above the threshold pump amplitude value. Properties of drifting
solitons are investigated.
