Highly sensitive refractive index sensing by epsilon near zero metamaterials

Abstract

We designed a highly sensitive refractive index sensor (RIS) with a simple and compact structure. In this regard, a metal-dielectric-metal (MDM) nanostructured thin film was considered to achieve a highly sensitive and tunable refractive index sensor in the near-infrared region. The MDM nanostructured thin film was used to determine the optical properties of incident light with transverse electric (TE) polarization at different angles. The effective relative permittivity obtained via numerical simulation confirms that the MDM thin film can be considered as an ENZ metamaterial. This is also verified by the results of group delay and group velocity in the structure. According to the results, the proposed RIS has a sensitivity of 1462 nm per refractive index unit, which is high enough compared to the state of the art. The significant advantage of our RIS is its small footprint, which is extensively used in electronic and photonic integrated devices. We think the proposed sensor can be used for future nanosensing applications, such as plasmonic metamaterial sensors.