Observation of white-light amplified spontaneous emission from carbon nanodots under laser excitation

A conventional laser irradiation method is applied to fabricate carbon nanodots (C-dots). By uniformly dispersing the C-dots into NMethylpyrrolidone (NMP) solution, white-light amplified spontaneous emission can be observed from the mixture under laser excitation at 266 nm. Peak wavelength and linewidth of the emission spectra are found to be around 450 and 120 nm respectively. It is verified that the presence of NMP enhances the emission efficiency of C-dots over the broad emission spectrum. This is because the excitation energy, which is not absorbed by the C-dots, is captured by the NMP and is subsequently transferred to the Cdots. Optical gain per peak power of the mixture at ~450 nm is found to be ~64 cm-1MW-1, which is about 39% higher than that without the use of NMP.