Two-Dimensional Reconfigurable Non-Hermitian Gauged Laser Array.

Topological effects in photonic non-Hermitian systems have recently led to extraordinary discoveries including nonreciprocal lasing, topological insulator lasers, and topological metamaterials, to mention a few. These effects, although realized in non-Hermitian systems, are all stemming from their Hermitian components. Here we experimentally demonstrate the topological skin effect and boundary sensitivity, induced by the imaginary gauge field in a two-dimensional laser array, which are fundamentally different from any Hermitian topological effects and intrinsic to open systems. By selectively and asymmetrically injecting gain into the system, we have synthesized an imaginary gauge field on chip, which can be flexibly reconfigured on demand. We show not only that the non-Hermitian topological features remain intact in a nonlinear nonequilibrium system, but also that they can be harnessed to enable persistent phase locking with intensity morphing. Our work lays the foundation for a dynamically reconfigurable on-chip coherent system with robust scalability, attractive for building high-brightness sources with arbitrary intensity profiles.