Application of Multilayer Planar Waveguide Structures to Sensing

E. Auguściuk and D. Dziąg Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland

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The multilayer planar step index wave-guides have been studied in detail for many years now. We examined gradient index waveguide, which was not thoroughly studied. In this article we have studied structures made from three, four, and five layers. We also used different substrates for this experiment. Gradient index wave-guides were made in Bk7 and Gevert's glass by the ion-exchange method. Then we put on it a thin layer of polymer and examined it again. Afterwards we applied a second layer of polymer achieving five-layer planar waveguide. Layers deposited on gradient index waveguide change the propagating conditions of light beam in waveguide structures. Using a generalized m-line spectroscopy method we determine thickness and refractive index of each layer of waveguide structure. In the next step, a simulation for step index planar wave-guides was run. The values for each layer were taken from previously calculated thickness and refractive index for multilayer gradient index wave-guides. Beam propagation method was used to obtain Neff only for step index waveguide structures to compare with Neff of gradient index waveguide structure. The changes in propagation of a light beam not only in waveguide (several modes) layer may be applied to sensing and controlling the direction of light in the waveguide structure (by depositing on it a polymer layer with the appropriate refractive index).

DOI: 10.12693/APhysPolA.118.1081 PACS numbers: 42.79.Gn, 42.82.Ds