Model of optical sensor on the base of MMI structures

The paper presents the research on waveguide sensors based on multimode interference structures. In the modeled systems, the applied sensor layer was used as the cover of the multimode section. The cover of the multimode section can be made of material sensitive to the changes of definite external conditions, and through a proper selection of this material the sensor can be adapted to the detection of various physicochemical quantities. In effect of the changes of optical parameters of the sensor layer, the propagation conditions change, which can be easily observed in the location changes of N-fold images of the input field. In the paper we have investigated and compared the systems based on waveguides having step index profile and gradient distribution of refractive index. We have demonstrated that the sensitivity of such systems can be adjusted through a proper selection of the dimensions of the multimode section.