Wang Yu-Chi, Li Heng, Hong Yu-Heng, Hong Kuo-Bin, Chen Fang-Chung, Hsu Chia-Hung, Lee Ray-Kuang, Conti Claudio, Kao Tsung Sheng, Lu Tien-Chang
Department of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering , National Chiao Tung University , Hsinchu 30050 , Taiwan.
Division of Scientific Research , National Synchrotron Radiation Research Center , Hsinchu 30076 , Taiwan.
ACS Nano. 2019 May 28;13(5):5421-5429. doi: 10.1021/acsnano.9b00154. Epub 2019 Apr 25.
Disorder is emerging as a strategy for fabricating random laser sources with very promising materials, such as perovskites, for which standard laser cavities are not effective or too expensive. We need, however, different fabrication protocols and technologies for reducing the laser threshold and controlling its emission. Here, we demonstrate an effectively solvent-engineered method for high-quality perovskite thin films on a flexible polyimide substrate. The fractal perovskite thin films exhibit excellent optical properties at room temperature and easily achieve lasing action without any laser cavity above room temperature with a low pumping threshold. The lasing action is also observed in curved perovskite thin films on flexible substrates. The lasing threshold can be further reduced by increasing the local curvature, which modifies the scattering strengths of the bent thin film. We also show that the curved perovskite lasers are extremely robust with respect to repeated deformations. Because of the low spatial coherence, these curved random laser devices are efficient and durable speckle-free light sources for applications in spectroscopy, bioimaging, and illumination.
无序正在成为一种制造随机激光源的策略，所采用的材料非常有前景，如钙钛矿，而标准激光腔对其并不有效或成本过高。然而，我们需要不同的制造方案和技术来降低激光阈值并控制其发射。在此，我们展示了一种在柔性聚酰亚胺衬底上制备高质量钙钛矿薄膜的有效溶剂工程方法。分形钙钛矿薄膜在室温下表现出优异的光学性能，并且在室温以上无需任何激光腔就能轻松实现激光作用，且泵浦阈值较低。在柔性衬底上的弯曲钙钛矿薄膜中也观察到了激光作用。通过增加局部曲率可以进一步降低激光阈值，这会改变弯曲薄膜的散射强度。我们还表明，弯曲的钙钛矿激光器对于反复变形具有极强的鲁棒性。由于空间相干性低，这些弯曲的随机激光器件是用于光谱学、生物成像和照明应用的高效、耐用且无散斑的光源。
