Unconventional Polarization-Dependent Lasing Behavior in Birefringent CsPbBr₃ Hybrid Mode Plasmonic Nanolasers

Semiconductor nanowires are sensitive to the polarization of light due to their one-dimensional structure and high dielectric contrast to the surrounding medium. This phenomenon enables configurations of polarization-sensitive nanoscale devices that can be potentially integrated onto a chip. Here, we demonstrate a hybrid plasmonic perovskite nanolaser that exhibits unconventional polarization dependence. Typical plasmonic nanolaser designs utilize a metallic substrate and a low-index buffer layer material. In this study, we use a birefringent CsPbBr₃ perovskite nanowire on a metal substrate separated by a thin Ta₂O₅ buffer layer, exhibiting a refractive index lower than that along the ordinary axes of the nanowire, but higher than that along the extraordinary axes. In these conditions, we experimentally show a lower lasing threshold when the incident field is orthogonally polarized, i.e., along the b-axis. This is due to stronger electric field confinement at the nanowire-buffer interface as shown in simulation when pumped by orthogonal polarized light. This polarization sensitivity is unique to the hybrid plasmonic configuration and is not observed in the photonic counterpart, such as a nanowire on a quartz substrate. Furthermore, we found that short plasmonic nanowires exhibit lower lasing thresholds in addition to a larger polarization dependence, contrary to longer plasmonic nanowires. Moreover, orthogonally polarized pumping induces a larger-emission blueshift than longitudinally polarized pumping, attributed to strong exciton-polariton interactions. This blueshift is pronounced in plasmonic nanowires with lower lasing thresholds. This polarization-sensitive plasmonic nanolaser with reduced lasing threshold has potential applications in nanophotonic integrated circuits and room-temperature perovskite polaritonics.