Low-temperature doping of lithium niobate for active waveguides application

Low temperature doping procedures are used to fabricate erbium doped annealed proton exchanged waveguides in X-, Y- and Z-cuts lithium niobate. The doping process occurs in melts of nitrates containing 10 wt. % of erbium nitrate at 350 degrees C. Under such conditions X-cuts contained up to 10 wt. % of Er in the waveguiding layer in spite of Y- and Z-cuts, where the erbium content was much lower. Such waveguides can be utilized in optical amplifiers.