Light funneling by spin-orbit-coupled chiral particles on an arbitrary order exceptional surface.

Optical systems at non-Hermitian exceptional points (EPs) have intriguing properties that promise novel applications in light manipulations. Here, we realize an arbitrary order exceptional surface (ES), i.e., a surface of arbitrary order EPs, in chiral particles that couple with each other via the photonic spin-orbit interaction mediated by a dielectric waveguide. The chirality of the particles enables selective excitation of the chiral dipole modes by linearly polarized light. The unidirectional coupling of the chiral dipole modes gives rise to the ES in the parameter space defined by the material loss and coupling distance of the particles. We apply the system to realize a light funnel that can convert free-space plane waves to guided waves and funnel the incident light energy into a ring resonator. The results can find applications in designing optical switches, on-chip conversion of guided waves, and harvest of light energy.