Modal Characteristics of Refractive Index Engineered Hybrid Plasmonic Waveguide

In this work, we proposed a novel design of a refractive index engineered subwavelength grating silicon-based hybrid plasmonic waveguide via the finite element method. The intensity integral (r) in the upper cladding can be controlled by varying the thickness (H
_Si
) of the top silicon layer. The highest evanescent field ratio of 0.85 is obtained at H
_Si
= 200 nm which allows the hybrid mode to confine in the low index medium and a large evanescent field resides in the upper cladding. The sensitivity of the waveguide is calculated by monitoring the change in the effective refractive index to the ambient refractive index. The maximum mode sensitivity of 0.7 is obtained. The spectral performance of the subwavelength grating (SWG) hybrid plasmonic waveguide (HPWG) based ring resonator design is studied which exhibits a sensitivity as high as 1000 nm/RIU which is higher than the previously reported values. We believe that the proposed waveguide scheme is an ideal candidate to produce highly sensitive lab-on-chip sensors.