  The interaction between light and non-trivial energy band topology allows for
the precise manipulation of topological quantum states, which has attracted
intensive interest in condensed matter physics. In this work, using
first-principles calculations, we studied the topological transition of
ferromagnetic (FM) MnBi$_2$Te$_4$ upon irradiation with circularly polarized
light (CPL). We revealed that the MnBi$_2$Te$_4$ can be driven from an FM
insulator to a Weyl semimetal with a minimum number of Weyl points, i.e., two
Weyl points in systems without time-reversal symmetry. More importantly, in FM
MnBi$_2$Te$_4$ with out-of-plane easy magnetization axis, we found that the
band dispersion of the WP evolves from Type-II to Type-III and finally to
Type-I when the light intensity increases. Moreover, we show that the profile
of the characteristic Fermi arc of Weyl semimetal phase is sensitive to changes
in light intensity, which enables efficient manipulation of the Fermi arc
length of FM MnBi$_2$Te$_4$ in experiments. In addition, for FM MnBi$_2$Te$_4$
with in-plane easy magnetization axis, the system becomes a type I Weyl
semimetal under CPL irradiation. With controllable band dispersion, length of
Fermi arc, and minimum number of WPs, our results indicate that CPL-irradiated
FM MnBi$_2$Te$_4$ is an ideal platform to study novel transport phenomena in
Weyl semimetals with distinct band dispersion.
