Experimental verification of selective refractive index sensor using single micro-ring resonator

Chemical and biological detection is vital across many fields. Optical sensors excel due to their high sensitivity, immunity to electromagnetic interference, and multiplexing capabilities. Refractive index (RI) sensors are ideal for on-chip detection, being highly sensitive and compatible with CMOS technologies like Silicon-on-Insulator (SOI), allowing for compact, cost-effective devices. However, traditional RI sensors lack selectivity and cannot identify substances in the medium. This study presents an SOI-based RI sensor using a single micro-ring resonator with multiple resonances over a 70 nm bandwidth around 1.55 μm. By measuring the real and imaginary parts of the refractive index at multiple wavelengths, it identifies substances through their unique dispersion profiles. The sensor was designed, fabricated, and tested in an SOI Multi-Project Wafer (MPW) run, with experimental results verifying its effectiveness.