Fig. 1. DuPont fiber molecular structure

Fig. 2. Flow chart

Fig. 3. Raman spectra of samples with different laser powers. (a) Scanning speed is 270 mm/s; (b) scanning speed is 300 mm/s

Fig. 4. Raman spectra of samples with different scanning speeds

Fig. 5. Raman spectra of samples with different defocusing degrees. (a) 13 mm; (b) 14 mm; (c) 15 mm; (d) 16 mm

Fig. 6. Laser defocusing diagram

Fig. 7. Microstructure of graphene. (a) Front view; (b) side view