Unveiling asymmetric topological photonic states in anisotropic 2D perovskite microcavities.

Photonic Rashba-Dresselhaus coupling in anisotropic microcavities offers a compelling platform for realizing unconventional topological states with non-zero Berry curvature. In this study, we explore a self-assembled two-dimensional hybrid structure composed of anisotropically oriented organic/inorganic halide perovskite layers confined within a microcavity. The strong optical anisotropies of these perovskite systems, driven by significant refractive index contrasts and robust excitonic resonances at room temperature, enable the emergence of synthetic magnetic fields that mediate photonic and polaritonic interactions. The interplay between polarization-dependent modes and spatial inversion symmetry breaking gives rise to strong photonic Rashba-Dresselhaus spin-orbit coupling, leading to distinct modifications in band topology and energy dispersions. These effects result in the formation of unconventional topological features, including non-zero Berry curvature and off-axis diabolical points, within the photonic and polaritonic bands at room temperature. Our findings reveal the critical role of optical and geometric anisotropies in engineering synthetic gauge fields for light, providing a versatile approach for designing photonic systems with novel topological properties. By leveraging the unique properties of halide perovskites and their ability to support both room-temperature excitons and large birefringence, this work advances the development of polaritonic platforms for applications in topological photonics and spinoptronics.