Non-Hermitian Skin Effect in a Su-Schrieffer-Heeger Chain of Nanocavities Through Nonreciprocal Loss

Achieving nonreciprocal optical transport in one dimension is of major significance while the reciprocity principle fundamentally limits its realization. Most of the current nonreciprocal devices rely either on magnetic materials or external time-varying driving, yet they often suffer from compatibility issues and device complexity that hinder wide applications. Recently, advances in non-Hermitian theory have suggested new possibilities of routing transport in an open-driven lattice system, called the "skin effect". The most well-known approaches for realizing one-dimensional skin effects require either anisotropic or long-range interactions among lattice sites to produce pseudomagnetic fields. Yet implementing such interactions typically requires devices of complex designs and large footprints.<br/>In this study, we present a theory model for realizing the one-dimensional skin effect via non-reciprocal loss, without requiring anisotropic or long-range hopping. We show that pseudo-magnetic fields emerge from a Su-Schrieffer-Heeger chain coupled with ancilla sites with nonreciprocal loss. We furthermore demonstrate how to implement the model with asymmetric photonic crystal nanobeam cavities. Numerical simulations using standard material parameters confirm clear nonreciprocity and skin localization of photonic modes, validating our theoretical model. Our study provides a new path toward magnetism-free non-reciprocal devices for unidirectional photon transport.