Abstract
Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties, which, however, is usually restricted by the disadvantages of the current fabrication methods. Here, by exploiting cylindrical focusing of a femtosecond laser on graphene oxide (GO) films, we successfully produce uniform subwavelength grating structures at high speed along with a simultaneous in situ photoreduction process. Strikingly, the well-defined structures feature orientations parallel to the laser polarization and significant robustness against distinct perturbations. The proposed model and simulations reveal that the structure formation is based on the transverse electric (TE) surface plasmons triggered by the gradient reduction of the GO film from its surface to the interior, which eventually results in interference intensity fringes and spatially periodic interactions. Further experiments prove that such a regular structured surface can cause enhanced optical absorption (>20%) and an anisotropic photoresponse (~0.46 ratio) for the reduced GO film. Our work not only provides new insights into understanding the laser-GO interaction but also lays a solid foundation for practical usage of femtosecond laser plasmonic lithography, with the prospect of expansion to other two-dimensional materials for novel device applications.
Highlights
Graphene analogs, such as graphene oxide (GO) and its reduced forms, are fascinating carbon materials due to the complementary properties endowed by the sp3sp[2] interconversion, revealing the substitutability and potential for industrialization of integrated graphene devices[1,2]
We demonstrate that the laser-induced gradient reduction of GO film from its surface to the interior plays a key role, which produces an inhomogeneous slab with the maximum dielectric permittivity (DP) at the surface and a smaller DP at deeper thicknesses that allows excitation of TEmode surface plasmons (TE-SPs)[28,29,30]
Compared with existing femtosecond laser processing technologies, such as direct writing and beam interference, the femtosecond laser plasmonic lithography (FPL) strategy is mainly based on incident light-SP interference and exhibits nonlinear optical characteristics, so it has superiorities of higher efficiency and stronger robustness against a range of perturbations
Summary
Graphene analogs, such as graphene oxide (GO) and its reduced forms (rGO), are fascinating carbon materials due to the complementary properties endowed by the sp3sp[2] interconversion, revealing the substitutability and potential for industrialization of integrated graphene devices[1,2]. Femtosecond laser-based processing, associated with the benefits of being facile, maskless, and efficient, is a qualified candidate for industrial development[14], and recently, it has been applied in the micro/nanomanufacturing of graphene analogs, such as typical patterning of GO films[15]. Due to the nonthermal and thermal effects during this processing, Zou et al Light: Science & Applications (2020)9:69 simultaneous in situ photoreduction can be realized just by removing the oxygen-containing functional groups of GO, which leads to controllability of GO’s morphology and reduction degree by changing the duration, intensity, or wavelength of the laser irradiation[15,16,17]. The most commonly adopted technologies for photoreduction of GO materials by femtosecond lasers are based on direct writing and beam interference[18,19]. Confined by the optical diffraction limit, the maximum processing accuracy of both common methods can only be comparable to the incident wavelength
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
