  Recently, man-made dielectric materials composed of finite-sized dielectric
constituents have emerged as a promising platform for quasi-bound states in the
continuum (QBICs). These states allow for an extraordinary confinement of light
within regions smaller than the wavelength scale. Known for their exceptional
quality factors, they have become crucial assets across a diverse array of
applications. Given the circumstances, there is a compelling drive to find
meta-designs that can possess multiple QBICs. Here, we demonstrate the
existence of two different types of QBICs in silicon-based metasurfaces:
accidental QBIC and symmetry-protected QBIC. The accidental QBIC evinces
notable resilience to variations in geometrical parameters and symmetry,
underscoring its capacity to adeptly navigate manufacturing tolerances while
consistently upholding a distinguished quality factor of $10^5$. Conversely,
the symmetry-protected QBIC inherently correlates with the disruption of unit
cell symmetry. As a result, a phase delay yields an efficient channel for
substantial energy transference to the continuum, endowing this variant with an
exceedingly high quality factor, approaching $10^8$. Moreover, the
manifestation of these QBICs stems from the intricate interplay among
out-of-plane electric and magnetic dipoles, alongside in-plane quadrupoles
exhibiting odd parities.
