Deep ultraviolet random laser disinfection

Abstract

Recently, the ineffectiveness of conventional antibiotic treatments against multidrug-resistant bacteria stimulated the development of novel effective disinfection technologies. Ultraviolet lasers, with several features, including high coherence, high directionality, monochromatic, and high intensity, were the ideal candidate light source for disinfection; however, conventional lasers are restricted by their inherent detriments such as high directionality, meticulous manufacturing, and the laser speckles. Random lasers have been considered powerful candidates for illumination sources due to their angle-free emission in recent years. However, their practical application remains scarce, and the result of using a deep ultraviolet random laser (DUV-RL) for disinfection has not ever been reported. Herein, the DUV-RL is realized by applying AlGaN multiple quantum wells (MQWs) and aluminum nanoparticles as the gain medium and plasmonic scattering centers. The proof of concept for the first DUV-RL disinfection in our study is examined by implementing this unique light source on model gram-negative bacteria (Escherichia coli). Additionally, the inherent angle-free emission characteristic of random lasers was confirmed and applied in treatment to achieve angle-free disinfection, which enables random lasers to overcome the major drawback of the high directionality of conventional lasers. Above all, the success of applying random laser systems in the disinfection arena fulfills the empty piece of current laser treatment. This research is expected to promote the development of DUV-RLs and enable them to compete with other light sources, such as mercury lamps and Ultraviolet-C (UVC) LEDs, in the near future.