Geometry symmetry-free and higher-order optical bound states in the continuum

Abstract Geometrical symmetry plays a significant role in implementing robust, symmetry-protected, bound states the continuum (BICs). However, this benefit is only theoretical many cases since fabricated samples’ unavoidable imperfections may easily break stringent geometrical requirements. Here we propose an approach by introducing concept of geometrical-symmetry-free but symmetry-protected BICs, realized using static-like environment induced zero-index metamaterial (ZIM). We find that robust BICs exist and are protected from disordered distribution multiple objects inside ZIM host its physical symmetries rather than ones. The geometric-symmetry-free regardless objects’ external shapes material parameters host. further show theoretically numerically existence those higher-order depends on number objects. By practically designing structural waveguide, confirmed, as well their independence presence symmetry. Our findings provide way realizing link properties to disorder photonic systems.