Role of edge inclination in an optical microdisk resonator for label-free sensing.
In this paper, we report on the measurement and modeling of enhanced optical refractometric sensors based on whispering gallery modes. The devices under test are optical microresonators made of silicon nitride on silicon oxide, which differ in their sidewall inclination angle. In our approach, these microresonators are vertically coupled to a buried waveguide with the aim of creating integrated and cost-effective devices. Device modeling shows that the optimization of the device is a delicate balance of the resonance quality factor and evanescent field overlap with the surrounding environment to analyze. By numerical simulations, we show that the microdisk thickness is critical to yield a high figure of merit for the sensor and that edge inclination should be kept as high as possible. We also show that bulk-sensing figures of merit as high as 1600 RIU(-1) (refractive index unit) are feasible.
Nanoscience Laboratory, Dept. Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy. d.gandolfi@science.unitn.it.
Davide
D
Gandolfi
Nanoscience Laboratory, Dept. Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy. fjaparicio@icmse.csic.es.
Fernando
F
Ramiro-Manzano
Nanoscience Laboratory, Dept. Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy. fjaparicio@icmse.csic.es.
Francisco Javier Aparicio
FJ
Rebollo
Center for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18,I-38123 Trento, Italy. ghulinyan@fbk.eu.
Mher
M
Ghulinyan
Center for Materials and Microsystems, Fondazione Bruno Kessler, via Sommarive 18,I-38123 Trento, Italy. pucker@fbk.eu.
Georg
G
Pucker
Nanoscience Laboratory, Dept. Physics, University of Trento, Via Sommarive 14, I-38123 Trento, Italy. lorenzo.pavesi@unitn.it.
Lorenzo
L
Pavesi
D015374:Biosensing Techniques / Q000295:instrumentation*; D055096:Optical Devices; D012031:Refractometry; D012825:Silicon / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry
D017655:Silicon Compounds; C032734:silicon nitride; D012825:Silicon