Thermally Evaporated MAPbBr₃ Perovskite Random Laser with Improved Speckle-Free Laser Imaging

Abstract

Metal halide perovskites (MHPs) are very promising materials for lasing applications due to their remarkable optical gain properties. Currently, most perovskite-based lasers are fabricated using lab-scale solution processing methods. The thermal evaporation (TE) method could be a promising alternative technology for scale-up fabrication with significantly improved reproducibility. Unfortunately, the fast and uncontrollable crystal growth process in thermal evaporation leads to defective films, and hence their laser performance usually falls behind their solution-processed counterparts. Here, we demonstrate high-performance random lasers and explore their speckle-free imaging application from perovskite thin films fabricated by an improved tri-source thermal co-evaporation approach assisted by a multifunctional Lewis base additive, triphenylphosphine oxide (TPPO). The optical gain of TPPO-passivated MAPbBr3 perovskite films is as high as ∼5 times that of the pristine one, and the corresponding gain lifetime is almost doubled after TPPO passivation. Due to the small grain size and compact confinement-induced strong multiple scattering, a random laser with threshold reduced by half and a high polarization degree of 78.4% is realized in thermally evaporated MAPbBr3:TPPO perovskite films. These findings would provide a possible route to scale up the manufacturing of high-performance perovskite materials and devices and open new perspectives for integrated speckle-free laser imaging systems.

Statistically Identified Dual Type Random Lasing from Carbon Dots

“…From a practical point of view, both coherent and incoherent RL emissions have several applications. For instance, coherent RL has been used for the generation of optical bits, barcode, and encryption. , All types of RL are advantageous light sources for speckle-free imaging, because of the low spatial coherence of RL emission. , In the following, we demonstrate the proof-of-concept use of our CD-based RL in speckle-free imaging under a conventional microscope setup.…”

“…Random lasers (RLs) are an emerging family of mirrorless laser-like light sources with foreseeable impact in next-generation photonic technologies, considering their simplicity in terms of design, low cost, and adjustable spatial coherence. − Unlike other lasers, where coherent narrowband light emission is achieved by coupling the gain medium to an optical resonator, RLs exploit the commonly observed phenomenon of light scattering inside a disordered structure . Typically, a colloidal dispersion of fluorescent nanoobjects, behaving as photonic gain media, is mixed with passive scatterers, and the blend can lead to an intense omnidirectional narrow-band laser-like emission if pumped over a certain threshold energy .…”

“…In contrast, coherent-type RL can stem from at least two different mechanisms: highly efficient scattering events determining the formation of closed “loops”, which effectively act as well-defined microcavities, , or the formation of extended modes characterized by very long light paths, capable of large amplification even through a nonresonant mechanism. , Coherent RL emission is advantageous for medical diagnostics, , random number generation, , photonic barcodes, and super resolution spectroscopy . In contrast, the low spatial coherence of incoherent RL is appealing for speckle-free imaging applications. , The two RL types can also coexist, and their relative weight is controlled by experimental parameters such as the concentration of scatterers and pumping conditions. The interplay between coherent and incoherent RL leads to intricate statistical properties of the emitted light which are theoretically interesting in photonics and physics of complex systems. ,, …”

Room-Temperature Near-Infrared Lasing from GaAs/AlGaAs Core–Shell Nanowires Based on Random Cavity

“…According to the random lasing theory, , the bigger the pumping area, the smaller the lasing threshold. In combination with the low spatial coherence of the random laser, it is an excellent illumination source for high-speed and speckle-free imagings. ,− …”

Lasing emission from ZnO hierarchical spherical microcavity

“…One type of powder laser is a semiconductor random laser composed of direct-gap semiconductors such as zinc oxide (ZnO) [21], gallium arsenide [22], gallium nitride [23,24], and semiconductor quantum dots [25][26][27][28][29][30][31][32][33]. Semiconductor random lasers have significant advantages for applications, such as the possibility of electrical excitation [34][35][36].…”