Recently, a research team from the State Key Laboratory of Strong-Field Laser Physics, Shanghai Institute of Optics and Precision Machinery (SIPM) of the Chinese Academy of Sciences (CAS), in collaboration with Hangzhou Institute of Advanced Studies (HIAS) of National University of Science and Technology (NUST), and Huazhong University of Science and Technology (HUST), has made progress in the research of scattering-free imaging of random lasers on thermally evaporated chalcogenides, and the related results are summarized in the title "Thermally Evaporated MAPbBr3 The results were published in ACS Photonics under the title "Thermally Evaporated MAPbBr3 Perovskite Random Laser with Improved Speckle-Free Laser Imaging".
Chalcogenide materials have excellent optical gain properties and are very promising for laser applications. Thermal evaporation deposition, a coating technology widely used in the semiconductor industry, is one of the technological trends for commercialized large-scale fabrication of chalcogenide devices. However, the rapid and uncontrollable crystallization of chalcogenide materials during thermal evaporation leads to many defects in chalcogenide films, which greatly affects the laser performance of chalcogenide films.
To address the above problems, the researchers proposed to slow down the crystallization rate and passivate the defects by introducing the multifunctional Lewis base additive triphenylphosphine oxide (TPPO), and finally prepared chalcogenide thin films with enhanced photoluminescence and nearly 5-fold improvement of optical gain coefficient. Power-dependent photoluminescence spectroscopy confirms the reduction of film defects, and transient absorption spectroscopy results indicate that the enhanced luminescence properties originate from the enhancement of the bimolecular complexation process. Based on these excellent luminescence properties, the researchers explored the stochastic lasing performance of thermally evaporated chalcogenide films and found that the stochastic lasing threshold of the films after the introduction of TPPO was significantly smaller than that of the original films. Meanwhile, the researchers applied the thermally evaporated chalcogenide films for the first time to laser scatter-free imaging, and when the random laser generated by the passivated films was used as the illumination source, the resulting images had lower scatter contrast (0.046) and higher contrast-to-noise ratio (8.218), which provided excellent imaging performance.
This study will provide new ideas for the large-scale production of chalcogenide materials and devices, and contribute to the development of thermally evaporated chalcogenide films for spontaneous radiation amplification and laser imaging applications.
Figure 1 Scatter-free imaging of random laser in chalcogenide thin film
