  Enhancing the light-matter interaction in two-dimensional (2D) materials with
high-$Q$ resonances in photonic structures has boosted the development of
optical and photonic devices. Herein, we intend to build a bridge between the
radiation engineering and the bound states in the continuum (BIC), and present
a general method to control light absorption at critical coupling through the
quasi-BIC resonance. In a single-mode two-port system composed of graphene
coupled with silicon nanodisk metasurfaces, the maximum absorption of 0.5 can
be achieved when the radiation rate of the magnetic dipole resonance equals to
the dissipate loss rate of graphene. Furthermore, the absorption bandwidth can
be adjusted more than two orders of magnitude from 0.9 nm to 94 nm by
simultaneously changing the asymmetric parameter of metasurfaces, the Fermi
level and the layer number of graphene. This work reveals out the essential
role of BIC in radiation engineering and provides promising strategies in
controlling light absorption of 2D materials for the next-generation optical
and photonic devices, e.g., light emitters, detectors, modulators, and sensors.
