Angular Interrogation-Based Self-Referenced LMR Sensor With High Sensitivity and High Figure of Merit

Abstract

In this letter, we present the first report on self-referenced lossy mode resonance (LMR) based refractive index (RI) sensor, which operates in angular interrogation scheme. The proposed design consists of a coating of ITO over a silica prism which is further coated by Teflon and ITO films. The proposed design was optimized for the best performance of the sensor and therefore the thickness of the ITO and Teflon layers were optimized for TE and TM polarization of light. For the TM polarization, the highest sensitivity and figure of merit (FOM) are 93.01°/RIU and 845.50 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> respectively and for TE mode, the highest sensitivity and FOM are 83.74°/RIU and 322.10 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> , respectively around 1.38 RI of analyte medium. To explain the sensing and self-referenced mechanisms, the electromagnetic (EM) field profiles were plotted using COMSOL which helps one understand the working of the sensor.