Ion-exchange across a direct-bonded interface

Summary form only given. Presented are the results of our initial study towards producing buried waveguides in BK-7 glass by intersubstrate ion-exchange. This method uses the direct bonding (DB) technique to provide a region of atomic contact between two, BK-7-type substrates, compositionally designed to create opposing potassium and sodium concentration gradients across the bonded interface, between which ion-exchange can take place. By taking this approach we have achieved a single-step buried ion-exchange mechanism with intrinsically low waveguide losses. It is the annealing phase used in DB that provides the key to this process.