Development of Optical Fibers with Embedded Gratings for Sensor and Signal Processing Applications
Final rept. Dec 1987-Dec 1989,
UNITED TECHNOLOGIES RESEARCH CENTER EAST HARTFORD CT
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Bragg gratings have been fabricated in the core of germanium-doped silica optical fibers using a photorefractive property of the glass. The process depends on an oxygen vacancy defect in the germania-silica core manifested by a strong absorption peak occurring in the uv at 245 nm. The absorption can be bleached by irradiation at the adsorbing wavelength leaving behind a residual small refractive index change. By irradiation with a holographic interference pattern, a phase grating of controlled periodicity is introduced into the fiber core. This report describes the grating fabrication technique and experiment work defining the optical characteristics of the grating and application to practical devices.