Plasmonic sensor for magnetic field detection with chalcogenide glass and ferrofluid materials under thermal variation in near infrared

Abstract In this paper, surface plasmon resonance based magnetic field sensor is simulated and analyzed in near infrared wavelength region (1557 nm) . The magnetic fluid is a colloidal material that can transform into different states depending on the strength of the external magnetic field (H). The structure of the sensor consists of chalcogenide (Ge28Sb12Se60) prism, silver layer, graphene monolayer, and a magnetic fluid (ferrofluid) film. Analysis is carried out using temperature-dependent complex refractive index of graphene (as per Kubo formulation) and silver layer (as per phonon-electron and electron-electron scatterings) along with the thermo-optic effect in prism and ferrofluid media. Angular interrogation method has been used. An extremely fine detection limit of 0.0037 mT at room temperature can be achieved. As large magnitude of figure-of-merit (FOM) as 1.7263 (mT)−1 can be achieved with the proposed magnetic field sensor. High refractive index of Ge28Sb12Se60 glass is helpful in ascertaining high spatial resolution while the non-linearity in Ge28Sb12Se60 may not be an issue as a low power laser source is required for the practical implementation of the proposed magnetic field sensor scheme.