High-resolution patterning of graphitic carbon structures in laser-induced graphitization of cellulose nanofiber film

In laser-induced graphitization, decreasing the linewidth of patterned structures is key to enhancing the potential in microdevice fabrication. In this study, we demonstrated that graphitic carbon structures with narrow linewidth can be directly patterned in laser-induced graphitization of cellulose nanofiber (CNF) film by immersing the film in CaI₂ solution. The linewidth of the structures increased with increasing laser power, indicating that the linewidth can be readily controlled. Based on the above findings, we patterned multiple concentric structures with precisely controlled linewidth to fabricate a Fresnel zone plate, which can focus laser light in the visible wavelength range.