Naturally Occurring Halloysite Nanotubes as Light Scatterers for Stable Random Lasing Applications

Naturally occurring halloysite nanotubes (HNTs) have attracted significant scientific interest due to their multifunctional behavior and biocompatibility. However, the application of HNTs in photonics is still unexplored. Here, natural HNTs with different lengths and diameters have been employed as passive scatterers for the generation of random laser (RL) emission from rhodamine B (RhB) in a colloidal phase. Upon pumping at 532 nm, mixed HNT-RhB disordered colloidal systems are shown to yield orange RL emission with a linewidth as small as & SIM;4 nm. Moreover, a statistical analysis of shot-to-shot correlations among RL modes reveals an obvious photonic paramagnetic to spin-glass transition with increasing pump energy, which is a unique statistical fingerprint of RL. Interestingly, besides acting as scatterers, the HNTs are also found to improve the photostability of RhB molecules. Indeed, HNTs help to better dissipate the excess energy deposited in the gain medium, thus protecting the dye from photodegradation and facilitating the achievement of RL. The results contribute to the theoretical understanding and technical development of low-cost RL devices based on widely available sources in view of multiple prospective applications in photonics.