A Graphene-Based THz Ring Resonator for Label-Free Sensing

In this paper, we report on a novel resonant THz sensor for label-free analysis. The structure consists of a silicon nitride dielectric ring resonator vertically coupled to a thin layer of graphene strip ring resonator on top. The cladding is assumed to be porous alumina on the top of the graphene strip, which enhances the interaction of the surface plasmon wave and the target molecules. Finite difference time domain analysis is used to systematically design the structure and to investigate the performance of the sensor. Our simulations show that the proposed structure has larger refractive index sensitivity and lower intrinsic quality factor with respect to the similar optical structure. It is also shown that the overall performance of the proposed structure in terms of figures of merit is superior to the performance of a similar optical structure. The proposed structure can be used for lab-on-a-chip sensing applications due to its compactness and is capable of being spectrally or spatially multiplexed for multi-analytic sensing.