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Femtosecond laser direct writing (FsLDW) is an emerging technology enabling arbitrary patterning via non-contact and maskless fabrication processes. The femtosecond pulse irradiation converts the graphene oxide (GO) into reduced graphene oxide (rGO) by removing the oxygen-containing groups of the GO, which is called photoreduction process. Because of its high printing resolution, sub-micron 2D optical structures can be printed based on GO and rGO as the base material. This study describes the fabrication of ultrathin GO/rGO optical components, which can be coated on arbitrary substrates. In the photoreduction using FsLDW, the resultant rGO’s optical properties such as refractive index, absorption coefficient, and surface reflectivity are varied on the input laser parameters, such as light wavelength, intensity, pulse repetition rate, and scan speed. To investigate the effects in detail, we performed parametric studies with different average intensity, pulse energy, and repetition rates at two wavelengths (343 nm and 515 nm). By adjusting the parameters, we could control the optical performances of the printed 2D optical structures. In addition, we studied the morphology changes of the rGO surfaces dependent on the laser parameters. The morphology plays an important role in transferring the rGO layer into the flexible polymer substrate. We will show the critical parameters for the morphology and propose the best conditions for the effective transfer of printed rGO patterns into the various flexible substrate.
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