Droplet microlasers: From fundamentals to multifunctional applications

Droplet microlasers are micro-scale lasers that utilize liquid droplets to construct optical resonators. Due to their notable attributes of flexibility, tunability, and reconfigurability, droplet microlasers exhibit great potential for developing integrated laser devices and applications in multi-dimensional sensing. In the past decade, substantial advancements have been made in both fundamental research and forefront applications of droplet microlasers. These advancements encompass novel lasing mechanisms, the development of full-color laser displays, applications in biological sensing, and the integration into detection systems. Motivated by the remarkable capabilities and pivotal strides, this review article aims to provide a lucid and comprehensive overview of the field of droplet microlasers. First, fundamental mechanisms inherent in droplet microlasers are illustrated, including the oscillation and wavelength-tuning mechanisms. Subsequently, the primary materials utilized for the fabrication of droplet microlasers are introduced. The review then encapsulates a summary of the diverse and multifunctional applications that droplet microlasers can undertake. Finally, the article concludes by deliberating on the future perspectives of droplet microlasers.