Surface-Emitting Perovskite Random Lasers for Speckle-Free Imaging

Abstract

Random lasers have been ideal illumination sources for speckle-free and high-speed imaging. Despite their successes, the real applications of random lasers are facing a long-standing challenge, i.e., the cumbersome size of the illuminating system. Herein, we demonstrate perovskite-based surface emitting random lasers (SERLs) and explore their applications in speckle-free imaging. The random lasers are generated by multiple scattering in a perovskite polycrystalline film sandwiched by two distributed Bragg reflectors. Owing to the tight confinement in vertical direction and large number of random resonances, the wavevectors of random lasers are dominated by their vertical components, and thus, multimode SERLs with a divergence angle of ∼3–5° and low spatial coherence are produced. By directly illuminating the patterns with the SERLs, the notable speckle noises of conventional optical images have been dramatically suppressed. This research shall provide a strategy toward the integrated spectral-free imaging systems.

Directing Random Lasing Emission Using Cavity Exciton-Polaritons

“…Due to the roughness of the MAPB layer, random lasing action is observed from the MAPB/PMMA sample. Such random lasing from perovskite polycrystalline thin films have already been demonstrated in the literature in MAPB thin layers [43,45]. The PL spectroscopy demonstrating the random lasing is shown in the section 2 of the supplementary.…”

“…directly from polycrystalline and nanocrystals thin films. This has indeed been demonstrated in iodine-based perovskites [27][28][29][30][31], chloride-based perovskites [32] and bromide-based perovskites [32][33][34][35][36][37][38][39][40][41][42][43][44][45].…”

Amplified Spontaneous Emission and Lasing in Lead Halide Perovskites: State of the Art and Perspectives

“…Anyway the multimode emission and the low spatial coherence propose random lasers as bright and cheap sources for applications in which coherence can produce artifacts, like the speckle patterns formation in illumination. A nice evidence of the perovskite random lasers potentialities as speckle free lighting sources was very recently obtained in MAPbBr 3 thin films deposited by spin coating and showing a morphology dominated by the aggregation of irregular perovskite islands with an in-plane size in the range 20-80 µm [47]. Coherent random lasing with a threshold of about 91 µJcm −2 was observed, under 100 fs pumping at 400 nm, ascribing the feedback to scattering at the islands edges.…”

Amplified Spontaneous Emission and Random Lasing in MAPbBr3 Halide Perovskite Single Crystals

“…RL in halide perovskites could found its applications in the speckle free imaging. [ 44 ] In all the above works either ASE or lasing were demonstrated, and even if both phenomena were reported in the same work, experiments were carried out in different structures.…”