Confining Light in Porous Perovskite Heterostructures for Light Amplification

Nanostructured porous media are capable of modulating light transport via diffusion or localization, while their combination with optical gain offers a solution to creating coherent light sources. Herein, we report on the development of a new class of optically active porous medium-porous perovskite heterostructures and demonstrate their potential in confining light via strong scattering for light amplification. Such heterostructures are chemically composed of 2D-networked CsPb2Br(5) and 3D networked CsPbBr3, which are attained upon direct water stimuli of 0D-networked Cs4PbBr6. Optical imaging reveals that light trajectories due to whispering gallery modes are formed in Cs4PbBr6 resonators to offer optical feedback for lasing. In contrast, light scattering due to structural inhomogeneity suppresses whispering gallery modes in porous heterostructures, while light is mainly confined in the pumping region. Despite the poor definition of microscopic cavities due to local disorder, the pump threshold of the porous heterostructure is only 1/3 to 1/5 that of Cs4PbBr6 and comparable to that of CsPbBr3 reported previously. Eigenvalue modeling was performed to analyze the eigenmodes, revealing that porous perovskite heterostructures support high-quality eigenmodes for lasing. The results suggest that perovskite heterostructures with interconnected porous scaffolds serve as promising complex nanophotonic systems for fundamental studies and potential applications.