Design guidelines for nanoparticle chemical sensors based on mode-splitting silicon-on-insulator planar microcavities

Abstract

In this paper, we report the design guidelines for optical systems based on mode-splitting microcavities in silicon-on-insulator (SOI) technology with the aim of optimizing chemical sensing platforms for revealing the presence of specific nanoparticles. In particular, through the analysis of the mode-splitting sensing principle, we point out the characteristics that a cavity should meet in order to be used as a single nanoparticle sensor, and we also identify some standard planar SOI geometries, i.e., ring- and disk-shaped resonant cavities, as candidates for mode-splitting-based nanoparticle chemical sensing. Moreover, we also envisage a hybrid SOI planar cavity, obtained by properly combining the physical features of SOI microring and microdisk, as a perfect candidate for improved performance in mode-splitting nanoparticle chemical SOI sensors. With a LOD of 30 nm, the hybrid configuration allows a theoretical resolution comparable to those achieved by ultrahigh quality factor resonators in low-loss silica technology.