Single-Mode Laser Arrays with Size-Invariant Loss Discrimination

Abstract

In conventional coupled oscillator lattices and laser arrays, expanding the active volume inevitably causes spectral crowding and degrades spatial uniformity, posing a long-standing barrier to high-power single-mode operation. We uncover a dissipative selection mechanism in sparse star networks that decouples modal selectivity from lattice size constraints. By engineering dissipative auxiliary couplings between a central hub and N peripheral resonators, the system establishes an exact star-Laplacian symmetry. This enforces a target eigenstate that is immune to all lossy channels while maintaining equal amplitude across all main nodes. All competing eigenstates break this symmetry, driving the auxiliary loss and opening a persistent, size-independent modal loss gap that prevents multi-mode competition. Realistic microring simulations validate the robustness of this dark-state isolation under electromagnetic dispersion and mechanism extension to arbitrary arrays is allowed when meets the system's exceptional point. By exploiting graph topology to bypass multi-mode competition, this work establishes a general route toward scalable high-power single-supermode laser arrays and robust state selection in coupled non-Hermitian systems.