Integrated Optical Slot-Waveguide Ring Resonator Sensor Arrays for Lab-on-Chip Applications

Abstract: This thesis treats the development of an integrated optical sensor array. The sensors areslot-waveguide ring resonators, integrated with on-chip surface grating couplers and lightsplitters, for alignment tolerant, real-time, refractive index sensing, and label-free biosensing.The work includes: the design of components and system layouts, the development offabrication methods, the fabrication of sensor chips, the characterization of the chips, andthe development of physical system models for accurate extraction of resonance wavelengthsin measured spectra.The main scientific achievements include: The evaluation of a novel type of nano-structuredoptical waveguide for biochemical sensing. The realization of an array of such slot-waveguidesensors, integrated with microfluidic sample handling, for multiplex assays. The first studyof the thermal behavior of slot-waveguide sensors and the discovery of unique temperaturecompensation capabilities.From an application perspective, the use of alignment tolerant surface gratings to couplelight into the optical chip enables quick replacement of cartridges in the read-out instrument.Furthermore, the fabrication sequence avoids polishing of individual chips, and thus ensuresthat the cost benefits of silicon batch micro-fabrication can be leveraged in mass production.The high sensitivity of the slot waveguide resonators, combined with on-chip referencingand physical modeling, yields low limits of detection. The obtained volume refractive indexdetection limit of 5 × 10?6 refractive index units (RIU), and the surface mass densitydetection limit of 0.9 pg/mm2, shows that performance comparable to that of commercialnon-integrated surface plasmon resonance sensors, made from bulk optical components, canbe achieved in a compact cartridge.