Athermalization of a silica-based waveguide with a UV-induced bragg grating on a crystallized glass substrate

Abstract

To realize athermal glass films, formation of Ge-B-SiO/sub 2/ and F-B-SiO/sub 2/ 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//spl deg/C was obtained in a 6GeO/sub 2/-13B/sub 2/O/sub 3/-81SiO/sub 2/ (mol%) core and 13B/sub 2/O/sub 3/-87SiO/sub 2/ (mol%) cladding waveguide or in a 13B/sub 2/O/sub 3/-87SiO/sub 2/ (mol%) core, 6GeO/sub 2/-13B/sub 2/O/sub 3/-81SiO/sub 2/ (mol%) grating layer and 6F/sub 2/-10B/sub 2/O/sub 3/-84SiO/sub 2/ (mol%) cladding waveguide on crystallized glass substrates with a thermal expansion coefficient of -2.0 /spl times/ 10/sup -6///spl deg/C. Such temperature sensitivity is one third of conventional waveguide Bragg grating devices.