To realize athermal glass films, formation of Ge-B-SiO 2 and F-B-SiO2 films by plasma-enhanced chemical vapor deposition (PECVD) was examined on several substrates with various thermal expansion coefficients. Waveguide Bragg gratings were fabricated by irradiation with a KrF excimer laser light through a phase mask. A temperature dependence of the Bragg wavelength as low as 4 pm/°C was obtained in a 6GeO2-13B2O3-81SiO2 (mol%) core and 13B2O3-87SiO2 (mol%) cladding waveguide or in a 13B2O3-87SiO2 (mol%) core, 6GeO2-13B2O3-81SiO2 (mol%) grating layer and 6F2-10B2O3-84SiO2 (mol%) cladding waveguide on crystallized glass substrates with a thermal expansion coefficient of -2.0 × 10-6/°C. Such temperature sensitivity is one third of conventional waveguide Bragg grating devices.
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