Single-mode lasing of CsPbBr perovskite NWs enabled by the Vernier effect

Inorganic lead halide perovskite (CsPbX 3 , X = Cl, Br, I) NWs (NWs) have been employed in lasers due to their intriguing attributes of tunable wavelength, low threshold, superior stability, and easy preparation. However, current CsPbX 3 NW lasers usually work in a multi-mode modal, impeding their practical applications in optical communication due to the associated false signaling. In this work, high-performance single-mode lasing has been demonstrated by designing and fabricating coupled cavities in the high-quality single-crystal CsPbBr 3 NWs via the focused ion beam (FIB) milling approach. The single-mode laser shows a threshold of 20.1 μJ cm −2 and a high quality factor of ∼2800 profiting from the Vernier effect, as demonstrated by the experiments and finite-different time-domain (FDTD) simulations. These results demonstrate the promising potentials of the CsPbX 3 NW lasers in optical communication and integrated optoelectronic devices. Single-mode lasing was obtained from CsPbBr 3 nanowires through designing and fabricating coupled cavities via FIB milling based on the Vernier effect.