Systematic modeling study of channel waveguide fabrication by thermal silver ion exchange

Abstract

A systematic study of thermal silver ion exchange used for the fabrication of optical channel waveguides is reported in a single-alkali glass. The diffusion equilibrium and diffusion dynamics are experimentally studied, and the concentration-dependent diffusion coefficients are determined. The relationship between the fabrication conditions, i.e., time, temperature, and melt concentration, and the induced waveguide refractive index profile is established. It is demonstrated that the diffusion equation can be solved, without use of any free parameters, to predict the refractive index profiles of both planar and channel waveguides. A 1.6 cm diameter integrated optic ring resonator, with a propagation loss of 0.1 dB/cm, is fabricated in a glass by thermal silver ion exchange. The induced refractive index profile is related to the optical characteristics of the functional device.

Low loss two-step ion-exchanged waveguides with high surface refractive index

“…As previously found, 42 for one-step Ag + − Na + ionexchanged waveguides, the induced surface refractive index change is directly proportional to the diffused Ag + ion concentration at the surface of the waveguides. We show here that, for the two-step ion-exchanged waveguides, both K + ions and Ag + ions contribute to the increase of the surface refractive index [ Fig.…”

Ion-exchanged glass waveguide technology: a review

“…82 Several methods have been used to measure ion concentration profiles. One destructive method uses etching away of thin consecutive layers and obtaining ion concentrations from the etchant solution by means of spectroscopy 83 or radiotracer analysis. Direct measurement of ion concentrations from the glass substrate edge facet can be obtained using an electron microprobe or scanning electron microscope for high-resolution scanning and analyzing the elements with energy dispersive x-ray spectroscopy or backscattered electron analysis.…”

Waveguide Fabrication Techniques

“…Instead, channel wave guides can be formed by either diffusion [92], ion implantation [93] or ion exchange [94] of suitable dopant atoms directly into the substrate, but through a mask. Such waveguides are often called buried channel waveguides since they lie beneath the surface.…”