From blue to near infrared: Carbon dots full-color tunable lasers for speckle free laser imaging

Carbon dots (CDs) are a kind of novel luminescent material for multi-color lasers duo to abundant of emission wavelength. The CDs tunable lasers had ether narrow tunable wavelength or complicated fabrication in previous publications. In this study, a simple one-pot solvothermal method is employed to synthesize four types of fluorescent CDs, emitting blue, green, orange-red, and near-infrared light, with photoluminescence covering a range from 445 nm to 721 nm by CDs surface modulation. Random lasers emitted from blue to near infrared regime are achieved by using CDs as gain medium. The CDs lasers are also employed as laser imaging light sources, enabling speckle-free full-color (from blue to near infrared) laser imaging. Images quality are found to be significant higher than that using traditional lasers or LEDs as light sources under the same circumstances. This work provides a simple one-pot fabrication method to develop wide band tunable CDs lasers and promotes the application of CDs lasers in full-color speckle-free laser imaging.