Highly sensitive sensors based on magneto-optical surface plasmon resonance in Ag/CeYIG heterostructures

Abstract

In this paper we present a new magneto-optical surface plasmon resonance (MOSPR) sensor using a dielectric magneto-optical thin film of Ce1Y 2Fe5O12 (CeYIG) and a metallic film of Ag. We demonstrate that by combining the low optical loss of Ag (ε =-62.485+4.331i) and the strong magneto-optical effect of CeYIG (ΦF = 2 × 104 deg/cm) at ∼1000 nm wavelength, a high figure of merit (FoM) for index sensing can be achieved. The device shows a factor of 20 improvement in the index resolution in comparison with ferromagnetic metal based MOSPR sensors at the same wavelength. By carrying out both analytical and numerical simulations, an optimized Ag/CeYIG MOSPR structure with the highest index sensitivity is achieved at the incident light wavelength of 1160 nm and the CeYIG thickness of 25 nm. The enhanced resolution of the DMOSPR sensor has been attributed to both the field enhancement at the sensing interface due to the high index of CeYIG films and, the high magneto-optical figure of merit of the CeYIG near infrared wavelength range.