Chiral Exciton‐Polariton Continuous‐Wave Perovskite Laser

ABSTRACT Chiral optical materials offer a route to generate circularly polarized laser emission for spin‐selective photonics, but realizing continuous‐wave (CW) circularly polarized lasing at room temperature has remained challenging. Here, a chiral exciton‐polariton CW laser is demonstrated using a microcavity strongly coupled with chiral 2D perovskite, (MBA) 2 PbI 4 . The resulting hybrid exciton‐polaritons undergo lasing with ultralow threshold at an onset CW pump intensity of 0.5 W·cm −2 at room temperature, orders of magnitude lower than all chiral halide perovskite lasers. The laser emission is intrinsically circularly polarized, with a luminescence dissymmetry factor (g lum ) about 0.30. Spectral tunability of the lasing wavelength is further demonstrated by adjusting the cavity thickness. The chiral polariton laser exhibits excellent stability under continuous operation, maintaining >95% of its output intensity over hours of CW pumping. The device represents a versatile platform with potential for spin‐optoelectronic applications and for exploring spin‐polarized quantum fluids of light at room temperature.