Thick hybrid silica-zirconia sol-gel film for single-step fabrication of channel waveguide

Abstract

An improved synthesis of inorganic-organic hybrid silica-zirconia sol-gel material has been developed, and it has controllable refractive index and can form ten-micron-thick film in a single spin coating process. The novel synthesis was realized by uniform hydrolysis and subsequent copolymerization of [3-(methacryloxy) propyl] trimethoxysilane and zirconium propoxide. The optical properties of the prepared sol-gel material was studied and characterized by a series of experiments. Compared with the sol-gel films reported before, the sol-gel film had good internal homogeneity and surface uniformity due to single layer structure. We employed the hybrid silica-zirconia sol-gel film in the singlestep fabrication of a dielectric channel waveguide on a quartz substrate. In the fabrication process, the sol-gel film was exposed to UV through a binary mask, and the exposed zone within the film formed a channel waveguide core because of its refractive index increase. The channel waveguide core was then covered again with a layer of the same kind of sol-gel film, and the unexposed zone within the sol-gel film, along with the new cover layer, formed the cladding of final dielectric channel waveguide. The novel sol synthesis enabled a precise control of the geometrical and optical parameters of the channel waveguide. In the 1.55 μm telecommunication window, the fundamental modes TE 00 and TM 00 in the channel waveguide had acceptable transmission losses of 1.20 ± 0.06 dB / cm and 1.79 ± 0.06 dB / cm, respectively.