Luminescent activation of planar optical waveguides in LiNbO3 with rare earth ions Ln3+ – a review

Based on the publications during the period 1990–2006, an attempt is made to summarize some of the important tendencies in integrated optics as well as the different techniques for activating lithium niobate by doping it with rare earth (lanthanide) ions. Luminescence properties of lanthanide ions in lithium niobate and in other hosts are reviewed in relation with their application in active thin film optical devices. The technological problems reported by different authors are commented. The possibilities for producing active waveguiding devices in lithium niobate only by low-temperature processes are discussed.