山西大学激光光谱研究所

Recently, the research team published a paper titled "Topological Photonic Alloy" in Physical Review Letters, a top-tier journal in the field of physics. Doctoral student Qu Tantao is the first author of the paper, and postdoctoral researcher Wang Mudi from The Hong Kong University of Science and Technology is the second author. Corresponding authors of the paper are Professor Chen Jun and Professor Zhang Lei from our university, as well as Professor Chen Ziting from The Hong Kong University of Science and Technology.

In this study, the team theoretically proposed and experimentally realized for the first time a novel disordered topological photonic system—the topological photonic alloy. The research demonstrates that a nontrivial topological phase can emerge in a disordered two-dimensional photonic crystal composed of randomly distributed non-magnetized (A) and magnetized (B) yttrium iron garnet (YIG) rods, thereby introducing the concept of an "alloy" into topological photonics. This system is achieved by randomly mixing non-magnetized and magnetized rods in an aperiodic two-dimensional photonic crystal configuration. Both theoretical and experimental results show that, even at low concentrations of magnetized rods, the photonic alloy can support topologically protected chiral edge states. This work provides a new platform for in-depth studies of the topological properties of disordered systems and offers a novel approach for more efficient fabrication of topological photonic systems.

Recently, the research group published a paper titled "Coexistence of reentrant localization and dynamical delocalization in a one-dimensional non-Hermitian quasiperiodic lattice" in Physical Review B. Doctoral student Wang Haoyu from our group is the first author, with Professor Zhang Lei serving as the corresponding author.
In this work, we discovered the coexistence of reentrant localization and dynamical delocalization in a one-dimensional non-Hermitian quasiperiodic lattice. Specifically, by studying a nonreciprocal dimerized lattice model with off-diagonal quasiperiodic disorder, we found that as the disorder strength increases, the system undergoes two localization transitions. Notably, this phenomenon does not occur in the corresponding reciprocal model.

Recently, our research group published a paper titled "Electric field controlled valley-polarized photocurrent switch based on the circular bulk photovoltaic effect" in the journal Physical Review B. The paper features our doctoral student Yang Yaqing as the first author, with corresponding authors being Professor Zhang Lei from our university, Professor Chen Jun, and Professor Wang Jian from Shenzhen University.
This research proposes a theoretical scheme based on a two-band Dirac model that enables switching of fully valley-polarized photocurrent between K and K' valleys using the bulk photovoltaic effect. By applying an out-of-plane electric field to two-dimensional valley materials, continuous tuning of the Berry curvature and its sign reversal is achieved. We discovered that the switching of fully valley-polarized photocurrent correlates with sign changes in the Berry curvature, accompanied by topological phase transitions such as quantum spin Hall and quantum valley Hall phases. Through first-principles calculations, we validated this theoretical scheme in monolayer BiAsI₂ and germanene. By applying an out-of-plane electric field, the corresponding valley polarization rate can be switched between 100% and -100%.