Ultra-high-Q microcavity operation in H2O and D2O
Optical microcavities provide a possible method for boosting the detection sensitivity of biomolecules. Silica-based microcavities are important because they are readily functionalized, which enables unlabeled detection. While silica resonators have been characterized in air, nearly all molecular detections are performed in solution. Therefore, it is important to determine their performance limits in an aqueous environment. In this letter, planar microtoroid resonators are used to measure the relationship between quality factor and toroid diameter at wavelengths ranging from visible to near-IR in both H2O and D2O, and results are then compared to predictions of a numerical model. Quality factors (Q) in excess of 10^8, a factor of 100 higher than previous measurements in an aqueous environment, are observed in both H2O and D2O.
Additional Information©2005 American Institute of Physics (Received 25 April 2005; accepted 8 September 2005; published online 7 October 2005) The authors would like to thank Prof. George Whitesides at Harvard University for his suggestion to investigate D2O. This work was supported by the DARPA Center for Opto-Fluidics at the California Institute of Technology.
Published - ARMapl05.pdf