Design of a New Type of Magneto-Optical Refractometric Sensors

In this article, two tunable all-dielectric magneto-optical refractometric sensors are presented to determine the Refractive index of the liquid analyte. The structures are composed of Y-Bi-Fe5O12 (Bi: YIG) arrays coated with an indium tin oxide (ITO) layer. These arrays are located on a layer of lithium niobate (LiNbO3). A p-polarized light wave with a wavelength of 630 nm in the range of 10°–60° and a magnetic field along the z-axis were used to produce the transverse magneto-optical Kerr effect (TMOKE). By applying these fields on the structure, according to the refractive index of the liquid analyte, the amplitude and angle of the TMOKE signal changes. The refractive index of the liquid analyte is discovered by comparing the obtained and referenced signals. Refractive indices of 1.35–1.41 were considered for the sensors because the refractive indices of a wide range of liquid analytes are within this range. The sensors were studied using ideal and quasi-real models. Non-flat and irregular random surfaces were used to design the sensor in the quasi-real model. The responses of the two sensors were compared to show their closeness. In the first design, the position of TMOKE signal was about one degree different for the two models. This difference was 0.25° in the second design. The values of TMOKE, sensitivity, and figure of merit (FoM) were obtained as 3.9714, 38.7°/RIU, and 3785 RIU−1, respectively, and the amplitude of TMOKE is significantly improved in these designs.