  Enhancing the light-matter interactions in two-dimensional materials via
optical metasurfaces has attracted much attention due to its potential to
enable breakthrough in advanced compact photonic and quantum information
devices. Here, we theoretically investigate a strong coupling between excitons
in monolayer WS$_2$ and quasi-bound states in the continuum (quasi-BIC). In the
hybrid structure composed of WS$_2$ coupled with asymmetric titanium dioxide
nanobars, a remarkable spectral splitting and typical anticrossing behavior of
the Rabi splitting can be observed, and such strong coupling effect can be
modulated by shaping the thickness and asymmetry parameter of the proposed
metasurfaces. It is found that the balance of line width of the quasi-BIC mode
and local electric field enhancement should be considered since both of them
affect the strong coupling, which is crucial to the design and optimization of
metasurface devices. This work provides a promising way for controlling the
light-matter interactions in strong coupling regime and opens the door for the
future novel quantum, low-energy, distinctive nanodevices by advanced
meta-optical engineering.
