Crystalline Line Formation from Lithium Heptagermanate in Lithium Germanate Glass.

The writing of continuous crystalline lines with an oriented structure, which were formed by the ferroelectric phase of Li2Ge7O15, was demonstrated under the action of a focused femtosecond laser beam in the interior bulk of glass with molar composition 20% Li2O and 80% GeO2. An unexpected difference was found between the crystalline phases precipitated in this glass under the action of a laser beam and on heat treatment in a furnace. The results obtained are of interest for devising crystalline channel waveguides in lithium germanate glass. [ABSTRACT FROM AUTHOR]