Figure 6
From: Measurement of bound states in the continuum by a detector embedded in a photonic crystal
Formation of BICs in photonic crystals. (a) PCS modes can be decomposed into basic waves. The basic waves are coupled to each other through in-plane wave propagation or via the continuum within near fields. The BIC is formed when all possible channels interfere destructively. (b) Basic waves in k-space. In the Γ-K direction, all radiative contributions cancel out because of symmetry. In the Γ-M direction, the symmetry is broken. These components can cancel as a result of accidental phase matching at special points in the photonic band structure, leading to the formation of BICs. The gray hexagon in the center indicates the Brillouin zone of the hexagonal lattice.
