CeNS Colloquium

Dr. Frank Vollmer
Harvard University

Optical resonance is created by localizing coherent light within a micro- or nanoscale structure so that it interferes constructively. Examples for such miniature optical resonators are silica microspheres and silicon photonic crystals. Because these optical resonators are almost immune to damping in a liquid, they are ultra sensitive biosensors: for example, single virus particles can be detected from discrete resonance frequency-shifts without requiring any chemical or fluorescent labeling of the particles. Sensitivity on the single particle level is possible due to the high quality (Q-) factor and the small size of the resonator.
Fabrication disorder is perceived as impediment to ideal resonator performance, and disorder ultimately limits the performance of any engineered device. However, when superimposed on a photonic band gap structure, disorder itself can induce light localization. We show such strong photon localization by disorder in photonic crystal waveguides. In this design concept, disorder and variability does not limit device performance, but instead is the basis for high-Q resonance. This new approach to engineering circumvents limitations posed by disorder, and illustrates a bioinspired design principle found throughout nature.