Fabrication of channel optical waveguides in glass by cw laser heating

By focusing the 488-nm line of an argon-ion cw laser beam with the aid of a microscopic objective on the surface of a moving piece of highly absorbing glass, low-loss channel optical waveguides at longer wavelengths are produced. At the laser beam focal point, glass is evaporated, producing grooves 2–8 μm wide. Strong confinement of light was observed beneath the grooves. An explanation for the occurrence of waveguiding is given together with experimental data on waveguide width as a function of applied laser power and sample speed. This method allows us to fabricate channel waveguides possessing periodic structure for frequency-selective guiding.