Maximising sensitivity of absorption-based ring resonator biosensors to changes in analyte absorption

Microring resonators are among the most common components in the standard photonic fabrication process and show promise for biosensing applications. In this study, we examine the conditions necessary for maximizing the sensitivity of ring resonators to changes in cladding absorption, which corresponds to the adsorption of analytes. Our studies indicate that increasing the radius of microrings enhances this sensitivity; however, there is an optimal radius that provides the highest SNR. Our results suggest that for a typical surface-loaded cladding loss of around 5 dB/cm, a radius of approximately 110 µm provides the optimal sensitivity point, considering a relatively maximal signal-to-noise ratio of around 12.