Patent ID: 8189981
Filing Date: 2012-05-29
Classification: G02B,G02F

Abstract:
1. A waveguide, comprising: a lithium niobate substrate having an upper surface; and a soft proton-exchanged layer embedded within the substrate, the soft proton-exchanged layer formed by exposing the lithium niobate substrate to a proton exchange solution including a proton exchange acid and a lithium salt of the proton exchange acid at a temperature of less than an atmospheric boiling point of the solution, followed by annealing the lithium niobate substrate under a vapor pressure of water preselected to inhibit protons in the substrate from forming water and evaporating from the upper surface of the substrate, and further comprising an overlayer comprising lithium niobate, the overlayer embedded between the upper surface of the lithium niobate substrate and the soft proton-exchanged layer, wherein the overlayer comprises a substantially defect free region extending between about 10 nm below the upper surface of the substrate and the soft proton-exchanged layer.