  We explore the stimulated emission of photons in non-spherical axion clusters
with or without the axion source from the superradiance of a rotating black
hole (BH). In particular, we focus on the cluster with the initial axion
distribution in the $(l,m)=(1,1)$ mode which mimics the shape of an axion cloud
induced by the BH superradiance. After establishing the hierarchy of Boltzmann
equations governing a general non-spherical axion-photon system, we examine the
evolution of photon and axion distributions in the cluster and possible
stimulated emission signals. In the case without the axion source, the
resultant signal would be a single photon pulse. As for the system with the BH
superradiance as the axion source, multiple pulses are predicted. We also show
that, for the latter case, the combined effects of stimulated emissions and the
axion production from the BH superradiance could reach a balance where the
axion cluster becomes uniformly and spherically distributed. Due to the energy
and temporal characteristics of the obtained pulses, we demonstrate that the
stimulated emissions from the axion cluster with axions sourced by the BH
superradiance provide a candidate explanation to the observed fast radio
bursts.
