COMPLETELY BURIED PLANAR WAVE-GUIDES FABRICATED IN GLASS USING A 2-STEP PURELY THERMAL K+ AND NA+ ION-EXCHANGE

The authors have succeeded in fabricating completely buried planar waveguides in glass using a two-step, purely thermal K+- and Na+- exchange. Ion-exchange conditions were experimentally determined, which ensured the complete burial of the waveguide and avoided problems of microcracking in the guiding layer. The refractive index profiles of both surface and buried waveguides were observed using a Mach-Zehnder interference microscope, and these profiles agreed well with theoretical predictions.