Reduced graphene oxide diffraction gratings from duplication of photoinduced azo polymer surface-relief-gratings through soft-lithography

Abstract

Reduced graphene oxide (RGO) diffraction gratings on glass substrates were fabricated by duplication of photoinduced surface-relief-gratings (SRGs) on azo polymer films through soft-lithographic methods. In the process, SRGs were inscribed on solid films of an epoxy-based azo polymer (BP-AZ-CA) by irradiation with interfering Ar⁺ laser beams, which were used as grating masters. Polydimethylsiloxane (PDMS) stamps with duplicated surface gratings were obtained by replica molding against the masters. Finally, by using the PDMS stamps and RGO dispersions as “inks”, the RGO diffraction gratings were fabricated through microcontact printing. The surface profiles and morphology of the as-prepared RGO gratings were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The periods of replicated RGO gratings were the same as those of the masters. Meanwhile, the amplitudes of the printed RGO gratings were determined by the “ink” concentration and the grating parameters of the PDMS stamps. By adjusting the preparation conditions, a series of RGO gratings with different periods and amplitudes were successfully fabricated. The optical properties of RGO gratings were characterized by diffraction efficiency measurements. The gratings showed typical thin grating characteristics with the diffraction efficiency (DE) of 7% for the green light. This new approach for preparing graphene gratings can provide a feasible way to explore the unique optical characteristics of RGO for developing graphene-based optical devices.