Plasmonic Ring Resonator Sensor with High Figure of Merit and Sensitivity Using Degenerate N-Doped Silicon for SPP Excitation

We present the modeling and numerical analysis of a highly sensitive plasmonic nano-ring resonator based on a degenerate n-doped silicon waveguide for bulk and adlayer sensing applications using the finite element method. The figure of merit of the sensor has been greatly improved without compromising the sensitivity value through careful optimization of the opto-geometric parameters to promote field confinement in the sensing region. To overcome the optical losses associated with conventional plasmonic devices, instead of metal, a degenerate n-silicon is used as a plasmonic material in this sensor. Additionally, it renders the device compatible with CMOS technology, enabling a simpler method for fabrication and integration into integrated circuits. A bulk refractive index sensitivity of 1734 nm/RIU with a very high figure of merit of 146 RIU\(^{-1}\) has been achieved, spanning the biologically relevant refractive index range (1.33\(-\)1.38 RIU). By considering a specific example of glucose solution in the ambient region, an average glucose sensitivity of 0.21 nm L/g has been observed. The sensor ’s performance as an adlayer biosensor was also examined, and a significantly high adlayer sensitivity measured is 6.8 nm/nm for a bio-layer of RI\(\sim\) 1.45  RIU. In photonic integrated circuits, our proposed structure can be employed as a nano-scale sensor that is compatible with CMOS fabrication technology.
Source: Plasmonics - Category: Biomedical Science Source Type: research