  Bound states in the continuum (BICs) have exhibited extraordinary properties
in photonics for enhanced light-matter interactions that enable appealing
applications in nonlinear optics, biosensors, and ultrafast optical switches.
The most common strategy to apply BICs in a metasurface is by breaking symmetry
of resonators in the uniform array that leaks the otherwise uncoupled mode to
free space and exhibits an inverse quadratic relationship between quality
factor (Q) and asymmetry. Here, we propose a scheme to further reduce
scattering losses and improve the robustness of symmetry-protected BICs by
decreasing the radiation density with a hybrid BIC lattice.We observe
significant increase of radiative Q in the hybrid lattice compared to uniform
lattice with a factor larger than 14.6. In the hybrid BIC lattice, modes are
transferred to Gamma point inherited from high symmetric X, Y and M points in
the Brillouin zone that reveal as multiple Fano resonances in the far field and
would find applications in hyperspectral sensing. This work initiates a novel
and generalized path toward reducing scattering losses and improving the
robustness of BICs in terms of lattice engineering that would release the rigid
requirements of fabrication accuracy and benefit applications of photonics and
optoelectronic devices.
