Physico-mathematical modeling of multi-step technology processes of single-mode waveguide fabrication in glass K-8 by ion exchange technique
Abstract
Physico-mathematical modeling of multi-step technology processes of single-mode waveguide fabrication in glass K-8 by ion exchange technique
Incoming article date: 23.11.2016Physico-mathematical modeling of multi-step processes of waveguide fabrication in glass K-8, based on the combined, solution of two-dimensional nonlinear diffusion equation, electrostatic equation and wave equation has been made. The diffusion equation was solved by application of implicit finite-difference two-layer Crank-Nicolson scheme with appropriate boundary conditions for each step of technology. The general case of three-step technological process is considered, including thermal ion exchange ”silver-sodium” in salt melt mixture AgNO3:NaNO3, electric field-assisted waveguide burial in salt melt NaNO3 and final step of glass substrate annealing. The technological conditions for the fabrication of single-mode waveguides, which have the size of mode field suitable for efficient butt coupling of waveguides with optical fibers at 1.55 micrometer wavelength, have been determined. The calculated mode size of waveguides is 10.6*9.5 um; the coupling efficiency with fiber is above 99%. Also the modeling of partially buried waveguide has been performed, where the field-assisted burial was made with the deposited mask covering the half-surface of ion-exchanged waveguide. Such waveguide has asymmetric distribution of refractive index and hybrid guided modes, and it may be the base of passive waveguide polarization TE-TM converters.
Keywords: integrated optics, optical waveguides, ion exchange in glass, electrically stimulated migration of ions, the nonlinear diffusion equation, waveguide mode