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Title: Laser-induced reduced-graphene-oxide micro-optics patterned by femtosecond laser direct writing
Authors: Low, Mun Ji
Lee, Hyub
Lim, Joel Chin Huat
Suchand Sandeep, Chandramathi Sukumaran
Murukeshan, Vadakke Matham
Kim, Seung-Woo
Kim, Young-Jin
Keywords: Engineering::Mechanical engineering
Issue Date: 2020
Source: Low, M. J., Lee, H., Lim, J. C. H., Suchand Sandeep, C. S., Murukeshan, V. M., Kim, S.-W., & Kim, Y.-J. (2020). Laser-induced reduced-graphene-oxide micro-optics patterned by femtosecond laser direct writing. Applied Surface Science, 526, 146647-. doi:10.1016/j.apsusc.2020.146647
Journal: Applied Surface Science
Abstract: Direct laser writing has emerged as a promising technology for facile and cost-effective single-step manufacturing of laser-induced reduced-graphene-oxide (LIRGO). Since LIRGO’s optical properties can be controlled during photoreduction process, laser-patterned micro-optics can work as light-weight diffractive optical elements over conventional bulk refractive optics. Here, we present ultra-thin diffractive LIRGO micro-optics patterned by femtosecond laser direct writing (FsLDW) with high spatial resolution and wide design flexibility based on the wide parametric tunability of femtosecond pulsed lasers over conventional continuous-wave or long-pulsed lasers. By extensive parametric control of average power (10–120 mW), pulse repetition rate (1–500 kHz) and scan speed (1–100 mm/s) in FsLDW, ultra-thin micro-optics were patterned at three patterning regimes: non-thermal photoreduction regime, thermal photoreduction regime, and ablation regime. The optical performances of Fresnel zone plates (FZP) fabricated under the three regimes were evaluated and compared; the results were 0.7%, 2.4%, and 3.8% for focusing efficiency, 12.2 µm, 13.2 µm, and 12 µm for focal spot size, 1.39 mm, 1.89 mm, and 1.77 mm for depth-of-focus for FZPs designed to 15 mm focal length with 10 concentric rings. This fabrication technique provides wide design flexibility to various planar LIRGO micro-optics for microfluidics, lab-on-a-chip, skin-attachable biomedical imaging, and micro photonic devices.
ISSN: 0169-4332
DOI: 10.1016/j.apsusc.2020.146647
Rights: © 2020 Elsevier B.V. All rights reserved. This paper was published in Applied Surface Science and is made available with permission of Elsevier B.V.
Fulltext Permission: open
Fulltext Availability: With Fulltext
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