The sensor application potential for the plasmonic hyperbolic metamaterial structures

Abstract

Sensors based on different types of guiding modes have been used for sensor applications for a long time. Those technologies were commercialized and actively used in different sensing applications. However, new challenges in biomedical research are requiring even better sensors. One of those new perspective technologies is plasmonic hyperbolic metamaterials. It was shown that those structures have a big potential for sensing. In order to compare these new guiding structures with traditional ones, we performed the analysis of sensitivity for different guiding structures: optical dielectric waveguide, surface-plasmon polaritons, long-range surface plasmon polaritons (LRSPP), plasmonic hyperbolic materials with a combination of metal and dielectric layers. All structures were placed on the BK7 glass substrate and we set wavelength at 1550 nm. We used the Si3N4 layer a waveguiding medium for the dielectric waveguide, we used gold for all plasmonic structures. The water layer on the top of all structures was used as a sensing area. For guiding modes coupling we used diffraction gratings for a few reasons. Firstly, there are no materials with a refractive index capable to couple guiding modes. Secondly, diffraction gratings provide compact, a planar design which is easier to keep the structure in the thermostatic condition And last but not least, we used coupling gratings with the same grating profile (sinusoidal) and the same corrugation depth so all guiding modes will be coupled the same way. Our results showed that plasmonic hyperbolic structures indeed have much higher sensitivity comparing with the traditional guided wave sensors based on dielectric waveguides and surface plasmon-polaritons.