ZnO-based random lasing and their sensing applications: a mini-review

Random lasers operate without a traditional resonator cavity compared with traditional lasers, instead relying on multiple scattering events within a disordered medium to amplify light. Their emission spectrum and spatial characteristics are determined by the disorder within the medium rather than by specific resonant modes. ZnO nanostructures are ideal for random lasers due to their strong light emission properties and high refractive index, facilitating efficient light scattering and amplification within the disordered medium. Additionally, their wide bandgap and ability to support both optical and electrical pumping make them versatile for various laser applications. ZnO-based random lasers unlock a future beyond high-resolution displays and foldable phones due to their speckle-free emission and a knack for scattering. In medicine, they promise label-free cellular insights, targeted cancer treatments, and miniaturized diagnostics. However, the future of ZnO-based random lasers demands careful crafting. Scalability, cost, and longevity remain hurdles. This review first addresses the synthesis parameters controlling ZnO nanostructures as gain media in random lasers. Then, recent advances in random laser design and performance are discussed, followed by an explanation of the pumping mechanisms. The review concludes by addressing the potential applications of ZnO-based random lasers, including sensors, imaging, medical and display technologies.