Complex Skin Modes in Non-Hermitian Coupled Laser Arrays

Abstract

From biological ecosystems to spin glasses, connectivity plays a crucial role in determining the function, dynamics, and resiliency of a network. In the realm of non-Hermitian physics, the possibility of complex and asymmetric exchange interactions (|kappa_ij| not equal to |kappa_ji|) between a network of oscillators has been theoretically shown to lead to novel behaviors like delocalization, skin effect, and bulk-boundary correspondence. An archetypical lattice exhibiting the aforementioned properties is that proposed by Hatano and Nelson in a series of papers in late 1990s. While the ramifications of these theoretical works in optics have been recently pursued in synthetic dimensions, the Hatano-Nelson model has yet to be realized in real space. What makes the implementation of these lattices challenging is the difficulty in establishing the required asymmetric exchange interactions in optical platforms. In this work, by using active optical oscillators featuring non-Hermiticity and nonlinearity, we introduce an anisotropic exchange between the resonant elements in a lattice, an aspect that enables us to observe the non-Hermitian skin effect, phase locking, and near-field beam steering in a Hatano-Nelson laser array. Our work opens up new regimes of phase-locking in lasers while shedding light on the fundamental physics of non-Hermitian systems.

References in corpus (4)

• Topological Origin of Non-Hermitian Skin Effects
• Efficient Light Funneling based on the non-Hermitian Skin Effect
• Observation of Chiral State Transfer Without Encircling an Exceptional Point
• Topological Modes in a Laser Cavity through Exceptional State Transfer

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• Localized states and skin effect around non-Hermitian impurities in tight-binding models
• Anderson localization versus hopping asymmetry in a disordered lattice
• Nonsymmetric evanescent coupling in photonics
• Giant non-reciprocity and gyration through modulation-induced Hatano-Nelson coupling in integrated photonics
• Topological $n$-root Su-Schrieffer-Heeger model in a non-Hermitian photonic ring system
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• Self-trapping and skin solitons in two-dimensional non-Hermitian lattices
• Work statistics and generalized Loschmidt echo for the Hatano-Nelson model
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• Non-Hermitian off-diagonal disordered optical lattices
• Optical non-Hermitian skin effect in two-dimensional uniform media
• Reconfigurable Non-Hermitian Soliton Combs using Dissipative Couplings and Topological Windings
• Hermitian and non-Hermitian topology in active matter
• Defect-driven incoherent skin localization
• Unifying Anderson transitions and topological amplification in non-Hermitian chains
• A non-Hermitian Su-Schrieffer-Heeger model with the energy levels of free parafermions
• Single-mode emission by phase-delayed coupling between nano-lasers
• Scaling of pseudospectra in exponentially sensitive lattices
• Efficient computation of coherent multimode instabilities in lasers using a spectral approach
• Exceptional horns in $n$-root graphene and Lieb photonic ring lattices