Lasing behavior of surface functionalized carbon quantum dot/RhB composites.

Random lasers have been extensively and intensively investigated due to their fundamental importance and promising applications. Here, we explored the lasing behavior of carbon quantum dot (CQD)/Rhodamine B (RhB) composites. CQDs exhibited a broad emission spectrum which overlapped with the absorption spectrum of the RhB dye. We investigated an approach wherein the -OH, -NH2 and -PO4 group functionalized CQD/RhB composites showed lasing behavior. The optical pumping of functionalized CQD/RhB composites exhibited lasing emission which is dynamically tunable as a function of the surface properties of CQDs at the laser wavelength of 532 nm by varying the pump energy. The PO4 -CQD/RhB composites showed a typical lasing emission with a linewidth of 3.2 nm at 587 nm at 1.86 mJ pump energy. We also demonstrated that the pH value of CQD solution played a key role on the lasing behavior of CQD/composites.