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The paper presents the results of theoretical analysis as well as the results of experimental research involving planar sensor structures with input grating couplers of the period Λ = 800 nm. In the theoretical part of the paper we discussed the influence of the parameters of a sensor structure on it sensitivities. The experimental part of the work presents the results of experimental research involving the influence of refractive index of the cover on the coupling characteristics of sensor structures with grating couplers. The full widths at half maximum (FWHM) were from 0.023° to 0.029°. For the investigated structures we estimated detection thresholds for the changes of refractive index of the cover and the changes of sensitive film thickness. It has been demonstrated that by the application of the elaborated structures we can detect minimal changes of the refractive index (Δnc)min = 2.1×10−6 when the refractive index of the cover nc = 1.333 and (Δnc)min = 1.0×10−6 when nc = 1515. For sensitive films of the thickness w < 100 nm, by using the elaborated structures, we can detect mean changes of the thickness along the values lower than 10−3 nm.

The aim of the presented investigations was to develop a technique of producing Bragg’s grating couplers on planar waveguides. Waveguides are obtained by means of the sol-gel technology. The introduction of a light beam into the structure of the waveguide is in the case of planar or strip optical systems always an essential technical problem, requiring simple and reproducible solutions without extending excessively the waveguide structure. The paper presents a technology of producing grating couplers by impressing the pattern of the network while forming the planar waveguide structure applying the sol-gel method. Some remarks concerning the sol-gel technology are also presented. The results of investigations on grating couplers obtained in such a way have been discussed, too.Attention has been drawn to the possibility of using such structures in optoelectronic sensors, particularly gas sensors, including sensors of water vapour as well as toxic gases.

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