Planar ion exchange and laser ablation for prototyping of integrated optics in glass

A new process for prototype manufacturing of integrated optical components was investigated. Sodium ions near the surface of a glass wafer are exchanged with silver ions, which creates a layer of increased refractive index. Subsequently, parts of the glass surface are ablated using a femtosecond laser. The resulting ridges determine the final optical waveguide structure. However, manufacturing-related roughness leads to high optical losses. To reduce these losses and to optimize the index profile, a second ion exchange with sodium ions is performed. These ions are introduced into the glass from all three ridge surfaces, causing the silver ions to migrate towards the ridge center. This results in a gradient index waveguide. We created a numerical model, to simulate the ion exchanges. Experiments were conducted, to determine the parameters for the ion exchange and the laser ablation. Based on the results, a process window was defined for each step, thus enabling the manufacturing of integrated optical components.