Ceramics-Silikáty 50, (3) 130 - 133 (2006)

Specially designed silicate glasses that contain various rare earth ions have recently become a very promising type of materials for photonics applications (e.g., optical amplifiers or lasers). Here we present a solution to the specific problem in fabrication of planar and channel optical waveguides by Ag⁺ ↔ Na⁺ ion exchange in Er⁻ and Yb⁻ containing glasses. From our previous experiments it follows that the routinely used conditions of this ion exchange are not suitable for fabrication of optical waveguides that would be used in optical amplifiers. To obtain samples with satisfactory optical properties (particularly, to minimize the optical losses in the waveguides), the total amount of Ag⁺ ions in-diffused into the surface layers of the glass has to be lowered. Moreover, the layers should be deepened and the total refractive index increment in the layers should be decreased to achieve the desired change of the refractive index profile. The experiments revealed that lowering of the Ag⁺ ions amount in the layers is possible by a substantial decrease of their concentration in the reaction melt. The redistribution of the silver ions in the layers (resulting in further change of the n(x) profile) was achieved by a combination of two fabrication steps - the ion exchange and the annealing (i.e., heating of the as-exchanged layers in air).