Design and simulation of a plasmonic density nanosensor for polarizable gases

Abstract

In this paper, an optical method of measuring the mass density of polarizable gases is proposed using a plasmonic refractive index nano-sensor. Plasmonic sensors can detect very small changes in the refracting index of arbitrary dielectric materials. However, attributing them to a specific application needs more elaboration of the material’s refractive index unit’s (RIU) relation with the introduced application. In a gaseous medium, the optical properties of molecules are related to their dipole moment polarizability. Hence, the theoretical index–density relation of Lorentz–Lorenz is applied in the proposed sensing mechanism to interpret changes in the gas’ refractive index and to changes in its density. The proposed plasmonic mass density sensor shows a sensitivity of 348.8 nm / ( gr / c m 3 ) for methane gas in the visible light region. This sensor can be integrated with photonic circuits for gas sensing purposes.