Fig. 1. (a) The absorption spectrum of carbon quantum dots and emission spectrum of DCM dye solution. (b) Emission spectrum of carbon quantum dots and an SEM image of carbon quantum dots.

Fig. 2. Experiment setup for PL spectrum collection of composite solution.

Fig. 3. (a) The SEM image of DCM dye with the concentration of 0.7% (mass fraction). (b) The emission spectra of DCM nanowires solution in a capillary tube. (c) The full width at half-maximum (FWHM) of emission spectra of DCM nanowires solution in a capillary tube as a function of the pump energy. (d) The SEM image of CQD/DCM composite and the distribution image of carbon element corresponding to the SEM image of CQD/DCM composite inside the red dashed circle. (e) The emission spectra of CQD/DCM solution in a capillary tube. (f) The FWHM of emission spectra of CQD/DCM composite solution in a capillary tube as a function of the pump energy.

Fig. 4. (a) The random lasing emission spectra of CQD/DCM-doped TiN nanoparticles (C/D/T) solution in a capillary tube. (b) The peak intensity and FWHM of emission spectra of C/D/T solution in a capillary tube as a function of the pump energy. (c) The normalized extinction section of TiN nanoparticles with diameters of 40 nm. (d) The electric field intensity distributions around TiN nanoparticles with diameters of 40 nm at the wavelength of 680 nm.

Fig. 5. (a) The time-resolved PL spectra of CQD, CQD/DCM, and DCM. (b) The FTIR spectra of pure DMSO solution, DCM solution (the solvent is DMSO), and CQD solution (the solvent is DMSO). (c) Schematic representation of the lasing process in the system of CQD/DCM nanowires composite-doped TiN particles.