Optimized Bent Part Coupling SiON Racetrack Resonators for Biological Sensing

In this paper, we investigate the optimized parameters of bent part coupling silicon oxynitride micro-racetrack optical resonators coupled to a straight waveguide, for an efficient design of label-free biosensor devices. A systematic engineering of waveguide-resonator characteristics for optimum geometry and field-overlap with analytes is proposed. Different parameters of system, such as coupling, intrinsic, and total quality factors of Q(kappa), Q(i), and Q(t), sensitivity (S) and figure of merit, or intrinsic limit of detection (ILOD), are examined with interest of taking into account the dispersion effect in calculations. To the best of our knowledge, considering dispersion effect in calculations has been proposed for the first time in bent part coupling racetrack resonator-based biosensors. We have shown the effective role of dispersion on the best optimized parameters of the biosensors. These investigations result in high amounts of S (435 nm/RIU) and Q(t) (>= 45000), simultaneously for the proposed biosensors. The devices have been optimized for operation at a wavelength of 850 nm. The biosensing performance of our biosensor is compared with lately reported theoretical and experimental investigations. Based on the ILOD calculations, the performance of our sensor structure is improved by a factor of 0.10 compared with a resonator-based biosensor, reported lately.