  This study presents a novel approach to activate a narrowband transparency
line within a reflecting broadband window in all-dielectric metasurfaces, in
analogy to the electromagnetically-induced transparency effect, by means of a
quasi-bound state in the continuum (qBIC). We demonstrate that the resonance
overlapping of a bright mode and a qBIC-based nearly-dark mode with distinct
Q-factor can be fully governed by a silicon trimer-based unit cell with
broken-inversion-symmetry cross shape, thus providing the required response
under normal incidence of a linearly-polarized light. Our analysis that is
derived from the far-field multipolar decomposition and near-field
electromagnetic distributions uncovers the main contributions of different
multipoles on the qBIC resonance, with governing magnetic dipole and electric
quadrupole terms supplied by distinct parts of the dielectric ``molecule.'' The
findings extracted from this research open up new avenues for the development
of polarization-dependent technologies, with particular interest in its
capabilities for sensing and biosensing.
