Ion-exchanged integrated waveguide structures

The authors describe an ion-exchange approach for producing waveguides that are circular, with a diameter of 50 μm for multimode fibers and from 5 μm to 10 μm for single-mode fibers. Such waveguides will permit high coupling efficiencies in both directions between the optical fibres and the waveguides. To avoid difficulties with diffusion masks, silver thin-film ion sources were chosen for the process. Several difficult glass materials were tested as substrates. At present, the fabrication involves only normal thin-film processes and photolithography for the guide pattern definition. Lift-off and sputter-etch techniques have been used to obtain 8-μm-wide waveguides. Since only planar processes are used, the ion-exchange technique is very suitable for batch processing and mass production.