Direct laser writing of graphene oxide patterns using femtosecond laser pulses with different repetition rates

Photoreduction-Insensitive GO/rGO Patterning Based on Multistep Femtosecond Laser Writing for Implementing Fresnel Zone Plates

“…14,15,19 A high transmission contrast may not be concurrently achieved alongside a minimized patterning linewidth of GO/rGO, from the viewpoint of photoreduction levels. 13,14 This limitation in FZP performance can be mitigated by introducing photoreduction-insensitive GO/ rGO patterning induced by fs-laser multistep writing, which allows for a miniaturized patterning linewidth as well as a high transmission contrast, with the assistance of a particular N fwt and a low repetition rate of 10 kHz.…”

“…The radical transmission contrast generated by a high degree of photoreduction of GO contrasts with the minimum patterning linewidth under the lowest extent of photoreduction. [12][13][14][15]20 In particular, it seems rather challenging to overcome such a trade-off. For instance, although both focusing efficiency and focusing resolution are improved by applying the Rayleigh−Sommerfeld diffraction theory, 21 the trade-off between focusing resolution and efficiency still exists in the optimized lens.…”

“…Femtosecond laser (fs-laser)-induced micro/nanopatterning of reduced graphene oxide (rGO), accompanying in situ photoreductions, has garnered considerable attention because its properties can be effectively adjusted using a facile and maskless method. − GO/rGO-based micro/nanostructures with mechanical flexibility, chemical/physical stability, and optical and electrical property tunability have been used in various applications, such as diffractive lenses, supercapacitors, photodetectors, and actuators. ,− With the removal of oxygen and carbon atoms, the patterning linewidth and photoreduction degree of GO/rGO are adjustable by controlling the fs-laser parameters encompassing the pulse energy and repetition rate. ,− At present, the most adopted technology for the photoreduction of GO via an fs-laser is direct writing based on a single-exposure process . However, when this method is used for enhancing the photoreduction degrees of GO/rGO, the side effect of the corresponding patterning linewidth widening becomes too obvious to be ignored. − The co-occurrence of tailoring the patterning linewidth and degrees of photoreduction hinders the application of fs-laser-induced GO/rGO patterning. ,− When the desired optical transmission, film thickness, and electrical conductivity come from high or medium degrees of GO/rGO photoreduction, it is unreasonable to expect to employ the minimum linewidth that can only be achievable at the lowest degree of photoreduction. Thus, the feature sizes of micro/nanodevices may be much larger than the minimum linewidth, when device performances are strongly subject to the optical and electrical properties of GO/rGO.…”

“…Benefiting from the fs-laser-induced micro/nanopatterning of GO/rGO, FZPs provide the advantages of ultrathinness, strong focusing, and high integrability and have been frequently reported in nano-optics and on-chip photonic systems. ,,, However, the above-mentioned concurrent variation in the degree of photoreduction and the patterning linewidth of GO/rGO leads to a trade-off between focusing resolution and efficiency. , It is known that focusing efficiency and resolution can be enhanced by attaining a distinct transmission discrepancy between adjacent binary zones and narrowing the width of the outermost zone, respectively. The radical transmission contrast generated by a high degree of photoreduction of GO contrasts with the minimum patterning linewidth under the lowest extent of photoreduction. − , In particular, it seems rather challenging to overcome such a trade-off. For instance, although both focusing efficiency and focusing resolution are improved by applying the Rayleigh–Sommerfeld diffraction theory, the trade-off between focusing resolution and efficiency still exists in the optimized lens …”

Laser Synthesis and Microfabrication of Micro/Nanostructured Materials Toward Energy Conversion and Storage

“…It demonstrated that the heat accumulation effect was critical for laser-induced transient heating of bakelite materials, and the subsequent instantaneous high temperature field localized in the microscale domain to generate the hierarchically macropores and mesopores. Young-Jin Kim et al [45] reported the direct laser writing of graphene oxide patterns using femtosecond laser pulses with different repetition rates. The results showed that the thermal accumulation effects dominantly affected the reduction degree and the linewidth of treated GO.…”