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Fabrication of a Doped Chitosan Surface Relief Grating Using Laser Ablation at a Wavelength of 193nm
Abdulsattar A. Aesa and Christopher D. Walton

In this paper, an ArF excimer laser 193 nm wavelength was used to realise a surface relief grating on thin films of biocompatible chitosan doped with rhenium cluster complex material. Using this type of laser is due to its ability for direct ablation and capability to fabricate grating structures. Laser direct writing technique was used to fabricate the surface relief gratings on the doped chitosan films. The grating by this technique was formed on thin films with different thicknesses; 2 µm and 300 nm. The grating period of 11.28 µm and sub-grating periods are reported. For grating profiles diffraction efficiency maps of 0-3rd diffraction orders have been obtained. The effects of overlapping pulse on the grating quality were analysed using SEM and discussed. The produced diffraction grating was characterised using different instruments: Scanning Electron microscopy (SEM), White Light Interferometer (WLI), Power Spectral Density (PSD) and far field Fraunhofer diffraction pattern. Also, DektakXT (Bruker) was utilised to measure the film thicknesses. HeNe laser in wavelength of 632.8 nm, 5 Watts was used to illuminated the grating to produce the diffraction pattern.
Application of surface relief grating is briefly discussed.

Keywords: Diffraction grating, Biocompatible materials, laser ablation, Excimer laser processing, Doped chitosan, surface relief grating

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