Si Ring Optical Resonators for Integrated On-Chip Biosensing

Abstract

Si ring optical resonators were fabricated for integrated on-chip biosensing, and tested for their sensing ability using sucrose solution. Resonance wavelength shifts were observed depending on the concentration of the solution. By detecting the output intensity change at a fixed wavelength, the detection sensitivity of the resonator became ten times larger than that obtained by detecting a resonance wavelength shift directly. Si ring optical resonators were applied to biomaterial sensing such as streptavidin and bacterial cells using the silicon-binding protein Si-tag, which enables receptors to be immobilized directly on the Si dioxide surface. For biosensing in aqueous solutions, the simulation results show that a wavelength of 1.3 µm is suitable. The results of this work indicate the possibility of further increasing sensing ability.