Polarization effects in K+–Na+ ion exchanged MMI structures with absorption cover

The paper concerns the polarization effects in gradient index MMI sensor structures made by ion K+–Na+ exchange. It has been shown both experimentally and based on the numerical calculation that for the K+–Na+ ion exchanged MMI structures, propagation conditions of light in multimode section vary considerably for each polarization. There are presented the possibilities of using this effect in application to gas sensing. Analyzed sensor structures are covered by WO3 absorbing nanolayers. Numerical analyses of MMI sensor are performed and modal attenuation coefficients are determined. The comparison between operation characteristics obtained for the TE and TM polarization is presented.