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"Photon crystal - supported surface electromagnetic waves: a tool to study dynamics of receptor-ligand interactions with living bacteria and cells, and to launch surface plasmons where they should not be"

S. K. Sekatskii
Ecole Polytechnique Federale de Lausanne
Lausanne, Switzerland


Recently, we proposed and developed ultrasensitive optical bio- and gas- sensor based on a properly designed Photonic Crystal (PC) supporting the propagation of bounded Electromagnetic Surface Waves (ESW) along the PC-medium to be studied interface. Our first results include ultrasensitive hydrogen detection exploiting surface plasmons propagated along thin (8 nm-thick) Pd layers, launch of surface plasmon in blue (405 nm) and UV spectral ranges along thin gold films and their use for ultrasensitive nitrogen dioxide detection Then this approach was used to support the surface plasmon propagation along thin ferromagnetic cobalt layer, to achieve unprecedently narrow (equal to 0.020 thus corresponding to the surface plasmon propagation length exceeding 0.1 mm) for the field magnetoplasmonic resonance (Transversal Magnetooptical Kerr Effect) with 11% magnitude. Note, that for all these cases, without a specially designed PC, this would be simply meaningless to speak about surface plasmons because the propagation length is just of the order of the wavelength.

For biosensing, we used ESW propagating along "bare"(no metal coating) PC-external medium (water) interface, specially treated to chemisorb protein layers. Besides quite large sensitivity, 0.2 pg/mm2, this approach has additional advantages due to the possibility to excite simultaneously s- and p-polarized surface electromagnetic waves having very different penetration depths into an external medium. This enables to segregate surface and volume effects, thus drastically increasing the reliability of the data obtained. Another advantage of our approach is the appearing possibility also to study interactions involving rather thick (of the order of one micron) objects such as bacteria, viruses, and certain cell organells - option unattainable for usual surface plasmon resonance-based detectors due to the short penetration depth of such plasmons. We have performed first experiments on antibody binding to living bacteria measured in real time by the PC ESW-based biosensor, obtaining the data essentially different from that earlier obtained on isolated bacterial membrane.

These results pave the way for further sensor and other applications of Photonic Crystal - supported surface waves, and the corresponding perspectives will be discussed. We also will briefly present our results on Fluorescence Resonance Energy Transfer Scanning Near-field Optical Microscopy, including the first observation of single molecule FRET SNOM images and possible applications to quantum computing.

Thursday, November 9, 2017
IQSE Seminar Room, 12:00 Noon
(578 MPHY)

Institute for Quantum Science and Engineering
Texas A&M University

Lunch (sandwich) will be served 15 minutes prior to start time