Fabrication and Characterization of Low-Loss, Sol-Gel Planar Waveguides

Lin Yang, S. Scott Saavedra, Neal R. Armstrong, John Hayes

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146 Scopus citations


Applications of planar integrated optical waveguide (IOW) technology to problems in surface spectroscopy and optical chemical sensing have been partly limited by the difficulty of producing high-quality glass IOWs. The fabrication of IOWs by the sol-gel method from methyltriethoxysilane and titanium tetrabutoxide precursors is described here. The physical, chemical, and optical properties of the films during and after high-temperature annealing were studied using a variety of analytical techniques. The results show that the catalyst used to accelerate the sol-gel reaction strongly influenced the optical quality of the IOW. HCl catalysis produced waveguides with propagation losses of ∼ 1 dB/cm, whereas in the case of SiCl4 catalysis, propagation losses were <0.2 dB/cm, a value significantly less than any previously reported for sol-gel- derived IOWs. An examination of film surface structure and morphology by scanning electron microscopy and atomic force microscopy showed that the SiCl4-catalyzed IOWs were significantly smoother and more homogeneous on a submicrometer scale than the HCl-catalyzed IOWs. The use of SiCl4 is thought to retard formation of a microheterogeneous network containing Si-rich and Ti-rich domains, which is favored with HCl catalysis and contributes to the higher observed losses.

Original languageEnglish (US)
Pages (from-to)1254-1263
Number of pages10
JournalAnalytical Chemistry
Issue number8
StatePublished - Apr 15 1994

ASJC Scopus subject areas

  • Analytical Chemistry


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