We present an apparatus for fabricating ion exchanged glass waveguides with reproducible characteristics. It consists of a vertical furnace with a uniform temperature zone, which is flat to within 1 °C over the sample length, a silica crucible for containing molten salt, a metallic sample holder made of either aluminum or stainless steel, and a motor-driven sample lowering system. The time and temperature are accurately controlled to produce waveguides of desired index profiles. ©1997 American Institute of Physics.