Al2O3 microresonators were realized for sensing applications of both passive and active devices. Passive microring resonators exhibited quality factors up to 3.2×105 in air. A bulk refractive index sensitivity of 100 nm/RIU was demonstrated together with a limit of detection of 10-6 RIU. Functionalizing their surface allowed for the label-free detection of the biomarker rhS100A4 from urine with a limit of detection of 3 nM. Furthermore, single-mode Al2O3:Yb3+ microdisk lasers were realized that could operate in an aqueous environment. Upon varying the bulk refractive index their lasing wavelength could be tuned with a sensitivity of 20 nm/RIU and a LOD of 3×10-6 RIU.
De Goede, M., Chang, L., Dijkstra, M., Obregon, R., Ramon-Azcon, J., Martinez, E., … Garcia-Blanco, S. M. (2018). Al2O3 Microresonator Based Passive and Active Biosensors. In International Conference on Transparent Optical Networks (Vol. 2018-July). IEEE Computer Society. https://doi.org/10.1109/ICTON.2018.8473820