Emission Control in Metal Halide Perovskite Lasers

Metal halide perovskites, as promising photovoltaic materials, have shown great potential in coherent light sources due to their unprecedented properties, such as solution processability, low cost, large and balanced carrier mobility, high optical gain, and tunable bandgap. With the rapid development in the material synthesis and nanofabrication technique, perovskite lasers have been realized in a variety of compositions, morphologies, dimensions, sizes, excitation schemes, and cavity configurations, giving rise to distinct emission characteristics. In this perspective, the latest progress in the mode control over perovskite lasers, including emission wavelength, mode number, direction, polarization, and orbital angular momentum, is systematically reviewed. Criteria for evaluating the effectiveness of the strategies to steer the emission are proposed and discussed. Lastly, the challenges and trends for the mode control of perovskite lasers are presented.