Control of birefringence in Ti:LiNbO3optical waveguides by proton exchange of lithium ions

The control of birefringence in Ti: LiNbO
3
optical waveguides by proton exchange is investigated in detail. It is shown that annealing of deep proton exchanged waveguides (
7-8 \mu
m) in an oxygen atmosphere allows precise control of the birefringence over a broad range of values. Even optically isotropic guides can be fabricated.