Erbium doping into lithium niobate and sapphire single crystal wafers

The possibility of localized doping by Er3+ diffusion at moderate (less tha n 500 degreesC) temperature was for the first time demonstrated for sapphir e single crystal wafers, The doping was achieved by immersing the substrate wafers into reaction melt containing small amounts of erbium salt. The cru cial point of the presented technology was a crystallographic orientation o f the used wafers, The most suitable orientation of the cuts was the "X-cut " with orientation (11-20). The strong anisotropy of the moderate temperatu re Er3+ doping into lithium niobate and sapphire was explained on the basis of the crystal structure of particular cuts.