High-sensitive plasmonic sensor based on Mach-Zehnder interferometer

Abstract

We design a novel, real-time and accurate plasmonic sensor made of asymmetric Mach-Zehnder Interferometer. Our plasmonic structure takes the advantage of surface-plasmon polaritons sub-wavelength confinement at the interfaces to fabricate nano- and micro-scale devices. The waveguides in the Mach-Zehnder Interferometer are made of lossy media, with positive and negative electromagnetic susceptibilities, including metamaterial, metal and graphene, interfaces with dielectrics. We compare the impact of media with different electromagnetic properties in the sensor structure on the sensor sensitivity and performance. The sensor is sensitive to the changes in the sample RI and is capable to work with different liquid and gas samples with different refractive indices. We introduce two configurations for the sensor with the sample in different domains along the structure to expand sensors applicability to different domains; the highest sensitivities reported for this sensor are 67.7THz/RIU, 69THz/RIU and 160THz/RIU for metal-, metamaterials- and graphene-based structures, respectively. We take the advantage of graphene to attain a tunable plasmonic sensor by applying a gate voltage to graphene in the sensor structure that shifts the sensor transmission peak to different frequencies and affects the sensor sensitivity. Our sensor structure has applications in liquid and gas chemical sensing, aerosol sensing, and environmental monitoring.