Alternative material titanium nitride based refractive index sensor embedded with defects: An emerging solution in sensing arena

Abstract

This article presents an ultra-compact refractive index sensor based on titanium nitride (TiN), a well-known alternative plasmonic material. The designed sensor consists of a straight waveguide, coupled with a groove and a Square-Ring Resonator (SRR). In addition, nanosized TiN dots are embedded in the waveguide and groove to enhance sensing performance. The spectral characteristics of the proposed sensor are numerically analyzed using the Finite Element Method (FEM). After extensive simulations, the most optimal structure provides a maximum sensitivity of 1074.88 nm/RIU and a Figure of Merit (FOM) of 32.4 and proves to be tolerant against probable real-life manufacturing defects. Furthermore, the incorporation of TiN equips the illustrated sensor with numerous advantages, for example, immunity to oxidation, optical tunability, capability to endure high-temperature, and compatibility with the standard Complementary Metal Oxide Semiconductor (CMOS) fabrication process. The major pitfall of traditional plasmonic metals is that the metals lack all these qualities, limiting real-life implementations of plasmonic devices. Therefore, the proposed model is superior to the conventional Metal–Insulator–Metal (MIM) setup and is expected to facilitate the development of practical, robust sensors.