Fig. 3: C2 symmetry collapse induced switching of GRs and BZF-BICs.
From: Brillouin zone folding driven bound states in the continuum
Calculated magnetic field profiles Hz of eigenmodes at Γ point and X point for unperturbed PhC (left panel), folded and un-folded modes at Γ point for gap perturbed (α = 0.3, middle panel) and radius perturbed (α = 0.3, right panel) PhCs. Modes at X point for unperturbed PhC show opposite symmetries under C2 operation regarding the high symmetry points at the air holes’ center (yellow dots) and at the middle of adjacent air holes (green dots). When a gap (radius) perturbation is introduced, the modes are moved from X point to Γ point, and their C2 symmetry collapses to the one with respect to the middle of adjacent air holes (air holes’ center).
