Conservative port-to-port funneling of light in nonlinear photonic lattices

Photonic systems that steer, guide, or focus light at the microscale are usually designed under passive and lossless conditions. However, Hermiticity, which governs wave evolution in such conservative environments, strictly limits how light can propagate and flow, preventing power from orthogonal inputs to merge into a single coherent channel. Here, we show that this fundamental barrier can be overcome through a nonlinear wave-dynamic process inaccessible under linear Hermitian conditions—the conservative funneling of light. We conceptualize this effect as an all-optical thermodynamic process, whereby wave packets, regardless of origin or coherence, are carried toward the lattice center and combine into a localized ground state. We identify a parametric regime of high powers where kinetic and nonlinear photon energies facilitate the irreversible transport of optical power. Our results demonstrate >70% port-to-port efficiency in a 20-channel system, establishing a robust framework for a universal, fully conservative light funnel.