Perfectly Nonreciprocal Diffraction of 1D Atomic Lattices with Geometrical and Structural Disorders

Geometrical and structural disorders are inevitable in fabricated photonic structures and can significantly impact their optical performance. Here, we investigate the robustness of perfectly nonreciprocal diffraction (PND) against these two types of disorder in one-dimensional (1D) atomic lattices. The significantly distinct diffraction phenomenon can be uncovered when the optical lattices introduce controlled random perturbations into the geometrical and structural parameters of each lattice site. Our results demonstrate that the forward diffraction spectrum exhibits remarkable resilience to both disorder types. Conversely, the backward diffraction spectrum is highly sensitive, displaying distinct responses to uncorrelated and correlated disorders. Specifically, PND persists only below a critical strength for uncorrelated geometrical disorder but is well preserved under correlated geometrical disorder. In stark contrast, PND shows strong robustness against uncorrelated structural disorder yet is significantly degraded by its correlated counterpart. These contrasting phenomena are attributed to whether the disorder introduces random spatial phase shifts that disrupt the destructive interference underlying PND. Our findings provide fundamental insights into wave transport in disordered potentials and offer a pathway for designing robust nonreciprocal devices resilient to fabrication imperfections.