Improving the performance of ring resonator refractive index sensor through structural modifications

In this work, different types of whispering gallery mode ring resonator structures such as strip, slotted, hybrid plasmonic mode, and subwavelength grating ring resonators are simulated using the finite difference time domain method (FDTD). The proposed devices are modeled to be used as refractive index sensor. The comparative analysis of strip, slotted, hybrid plasmonic mode, and subwavelength grating ring resonators is done in terms of sensitivity, Q factor, and figure of merit (FOM) to find out the most suitable device according to the requirement. Additionally, the effect of waveguide width on sensitivity and Q factor is analyzed. The analysis shows that, compared to other simulated whispering gallery mode ring resonator sensor designs, the subwavelength grating ring resonator produces the best sensitivity of 1012 nm/RIU, and the slotted ring resonator produces the best FOM of 1610.