Topological Anderson Phase Transitions in Y-shaped Plasmonic Valley Metal-slabs

Throughout history, all developmental trajectories of civilization - encompassing progress, creation, and innovation - have fundamentally pursued the paradigm shift 'from disorder to order'. In photonics, investigations into disordered systems have primarily focused on foundational principles governing signal diffusion and localization. This paper addresses terahertz device development by examining the dual role of disorder in photonic systems: while potentially compromising optical transmission stability, it simultaneously inspires innovative topological protection mechanisms. Building upon the symmetry-breaking induced valley-Hall topological Anderson phase transition in Y-shaped metallic structures, we achieve valley Chern number modulation through random rotation of constituent units, demonstrating progressive emergence of in-gap topological states with increasing disorder parameters and observing topological negative refraction phenomena. Furthermore, an effective Dirac two-band model is established to quantitatively characterize the evolution of bulk transport states under disorder variation. By strategically regulating disordered configurations to induce valley-Hall topological Anderson phase transitions, this research provides new pathways for overcoming critical technical challenges in terahertz devices, particularly transmission loss limitations.