The potential of ion exchange in sol–gel derived photonic materials and structures

Sol–gel is a very convenient technique for the fabrication of high quality thin glass films, optical planar waveguides and photonic bandgap structures. Ion exchange, on the other hand, is a well-established technique to fabricate high quality waveguides in glass and integrated optical amplifiers made by this technique are commercially available. The possible integration of the sol–gel and ion-exchange techniques for the fabrication of passive and active (rare-earth doped) channel waveguides in integrated optic devices has recently gained interest. A general overview of the fabrication of passive and active films and planar waveguides by sol–gel is followed by a brief description of waveguide fabrication by ion exchange and the possible integration between the two processing technologies.