Engineering an exceptional point from a single bound state in the continuum via symmetry-breaking perturbations.

To overcome the spectral invisibility of bound states in the continuum (BICs) and the extreme linewidth constraints of exceptional points (EPs), this work proposes a novel, to the best of our knowledge, design strategy. Asymmetric rectangular holes are introduced into a symmetry-protected BIC template to theoretically engineer a second-order EP with a tailored quality factor (approximately 10³). Systematic perturbation tests demonstrate that in the vicinity of the EP, the frequency splitting follows a square-root scaling relationship, with power-law exponents centered near 0.5. This universal square-root scaling, which stands in stark contrast to the quasi-linear response (with exponents clustering near 0.0) far from the EP, confirms the singular sensitivity in the vicinity of the EP. Our work demonstrates a feasible approach to realizing and utilizing EPs in robust, passive photonic platforms, offering a potential pathway to bridge the gap between ideal BIC confinement and EP-enhanced sensing.