Photosensitive mechanisms in germanosilicate optical fiber and planar waveguides.

Abstract

In this thesis, the microscopic and macroscopic mechanisms for photosensitive grating formation in germania-doped silica optical waveguides are investigated. The wavelength dependent response of grating growth is examined in doped-core optical fibers and correlated to defect generation in the material. In addition photosensitive grating studies carried out in a series of compositionally pure germanosilicate sol-gel thin-film waveguides are evaluated. The effects of both sample composition and controlled atmosphere heat treatments on the photosensitivity, UV absorption and fluorescence of the films are analyzed. Finally, ultraviolet bleaching experiments are conducted on the films and the observation of band growth and bleaching is evaluated in light of existing models for photosensitive effects in these materials. Based upon the experimental results, a microscopic model is proposed to explain photosensitivity and photosensitive Bragg grating formation in the germania-silica system.