Analyses of Ion-exchanged Glass Optical Waveguides by Means of Secondary Ion Mass Spectroscopy: Condensation of Impurity Halide Ions at the Surface

Abstract

We analyzed the chemical composition of K⁺-exchanged glass optical waveguides (OWGs) by secondary ion mass spectroscopy. Extensive condensation of impurity halide ions took place at the surface of the OWGs in the ion-exchanging and annealing processes. The condensation of Cl^- ions is likely a cause of the abnormal behavior observed for soda-lime glass OWGs; that is, a guided mode having appeared during the annealing did not disappear even after long annealing. Moreover, it was suggested that a space charge layer was formed at the OWG surfaces owing to the condensation of the halide ions.