Metasurface-tunable lasing polarizations in a microcavity

Manipulating polarization states of microlasers is essentially important in many emerging optical and biological applications. Strategies have been focused on using external optical elements or surface nanostructures to control the polarization state of laser emission. Here we introduce a strategy for manipulation of laser polarization based on metasurfaces through round trips of photons confined inside an active optical cavity. The roles of intracavity metasurfaces and light–meta-atom interactions were investigated under a stimulated emission process in a microcavity. Taking advantage of strong optical feedback produced by the Fabry–Pérot optofluidic microcavity, light–meta-atom interactions are enlarged, resulting in polarized lasing emission with high purity and controllability. Depending on the metasurface structural orientation, the polarization state of lasing emission can be actively modulated as linearly polarized or elliptically polarized with different degrees of circular polarization at a source within the microcavity. This study provides insight into fundamental laser physics, opening possibilities by bridging metasurfaces into microlasers.