Second order optical nonlinearity of proton exchanged lithium niobate and lithium tantalate waveguides

This paper presents the influence of the phase state of proton exchanged (PE) LiNbO/sub 3/ and LiTaO/sub 3/ waveguides on the second-order optical nonlinearity by using reflected second harmonic generation (SHG) measurements from the polished waveguide end face in different H/sub x/Li/sub 1-x/NbO/sub 3/ and H/sub x/Li/sub 1-x/TaO/sub 3/ phases: as-exchanged and annealed proton-exchanged (APE) waveguides, high-temperature proton-exchanged (HTPE) waveguides, as well as reverse proton exchanged (RPE) waveguides, and proton exchanged waveguides in stoichiometric and MgO-doped LiNbO/sub 3/ crystals.