A high-sensitive sensor and band-stop filter based on intersected double ring resonators in metal–insulator–metal structure

In this paper, a waveguide coupled with two intersected cavity ring resonators, based plasmonic sensor has been proposed, which is compact in design with higher sensitivity. The structural parameters of the sensor has a key role in its sensitivity and transmission spectrum, and are analyzed using the finite-difference time-domain method embedded in the commercial simulator Rsoft. The results yield a linearity between the refractive index of the material under testing and its resonance wavelengths. The maximum achieved linear sensitivity was S = 2448 nm/RIU for the second mode and S = 1120 nm/RIU for the first mode, its corresponding sensing resolution is $$4.08 \times {{10}^{-6}}$$ RIU for mode 2 and $$8.98 \times {{10}^{-6}}$$ RIU for mode 1, which makes our design a promising candidate for high performance nano-sensors and bio-sensing devices. It’s also applicable as a band-stop filter, due to the fact that the positions of transmission peaks and bandwidth can be easily manipulated, by adjusting both the inner radius and the distance between the centers of the two ring resonators.