Fabrication Of SiO₂-Al₂O₃ Waveguide Films And Splitters

With the rapid development of optical fiber communication and integrated optics, optical waveguide on silicon substrates have focused on research and application in the field of optical fiber communication and optoelectronics. Research and development of waveguide devices are based on the fabrication of waveguide films. Owing to sol-gel method with convenient fabrication films and simple technique, it is applied widely to deposit waveguide films. In this paper, we focus on fabrication of optical waveguide on silicon substrates by sol-gel method.Above all, photosensitive SiO₂/Al₂O₃ solution was fabricated by sol-gel process from precursors of Methacryloxypropyl trimethoxysilane （MAPTMS）, Aluminum sec-butoxide and 1-Phenyl-1-3-butanedione （BzAcH）. The SiO₂/Al₂O₃ film was fabricated on Silica-based on silicon by one-step dip-coating. Its thickness is 4.3μm and the refractive index is 1.559. Utilizing its photosensitivity , single mode waveguide , 1×N （N=2, 4） Y-branch splitters and 1×N （N=4, 8） multimode interference splitter were prepared by exposure to UV-light though mask. Besides, we made the light though the fiber input the single mode waveguide, 1×2 Y-branch and 1×4 multimode Interference splitters. The result indicated that the waveguide devices could make 1.53-1.56 μm wavelength light transmit in them.Furthermore, the organic-inorganic coupling structure was formed by the addition of polyethylene glycol （PEG） in the above SiO₂/Al₂O₃ sol, and the thickness of the film has efficiently been increased. The SiO₂/Al₂O₃/PEG film with the thickness of 15 μm was obtained heat-treated at 200℃ for one hour. Utilizing the photosensitivity, the gel films were irradiated with UV light through a mask, leached and heat-treated at 200℃ for one hour, and then the waveguide array the line-space of 100μm were obtained.