Silicon photonic resonators, implemented using silicon-on-insulator substrates, are promising for numerous applications.
The most commonly studied resonators are ring/racetrack resonators. We have fabricated these and other resonators including
disk resonators, waveguide-grating resonators, ring resonator reflectors, contra-directional grating-coupler ring
resonators, and racetrack-based multiplexer/demultiplexers.
While numerous resonators have been demonstrated for sensing purposes, it remains unclear as to which structures
provide the highest sensitivity and best limit of detection; for example, disc resonators and slot-waveguide-based ring
resonators have been conjectured to provide an improved limit of detection. Here, we compare various resonators in
terms of sensor metrics for label-free bio-sensing in a micro-fluidic environment. We have integrated resonator arrays with
PDMS micro-fluidics for real-time detection of biomolecules in experiments such as antigen-antibody binding reaction
experiments using Human Factor IX proteins. Numerous resonators are fabricated on the same wafer and experimentally
compared. We identify that, while evanescent-field sensors all operate on the principle that the analyte's refractive index
shifts the resonant frequency, there are important differences between implementations that lie in the relationship between
the optical field overlap with the analyte and the relative contributions of the various loss mechanisms.
The chips were fabricated in the context of the CMC-UBC Silicon Nanophotonics Fabrication course and workshop.
This yearlong, design-based, graduate training program is offered to students from across Canada and, over the last four
years, has attracted participants from nearly every Canadian university involved in photonics research. The course takes
students through a full design cycle of a photonic circuit, including theory, modelling, design, and experimentation.