Fano lineshapes of 'Peak-tracking chip' spatial profiles analyzed with correlation analysis for bioarray imaging and refractive index sensing
Type
Conference PaperKAUST Department
Advanced Nanofabrication, Imaging and Characterization Core LabCore Labs
Imaging and Characterization Core Lab
KAUST-HKUST Micro/Nanofluidic Joint Laboratory
Material Science and Engineering Program
Physical Science and Engineering (PSE) Division
Date
2013-05-22Permanent link to this record
http://hdl.handle.net/10754/555710
Metadata
Show full item recordAbstract
The asymmetric Fano resonance lineshapes, resulting from interference between background and a resonant scattering, is archetypal in resonant waveguide grating (RWG) reflectivity. Resonant profile shift resulting from a change of refractive index (from fluid medium or biomolecules at the chip surface) is classically used to perform label-free sensing. Lineshapes are sometimes sampled at discretized “detuning” values to relax instrumental demands, the highest reflectivity element giving a coarse resonance estimate. A finer extraction, needed to increase sensor sensitivity, can be obtained using a correlation approach, correlating the sensed signal to a zero-shifted reference signal. Fabrication process is presented leading to discrete Fano profiles. Our findings are illustrated with resonance profiles from silicon nitride RWGs operated at visible wavelengths. We recently demonstrated that direct imaging multi-assay RWGs sensing may be rendered more reliable using “chirped” RWG chips, by varying a RWG structure parameter. Then, the spatial reflectivity profiles of tracks composed of RWGs units with slowly varying filling factor (thus slowly varying resonance condition) are measured under monochromatic conditions. Extracting the resonance location using spatial Fano profiles allows multiplex refractive index based sensing. Discretization and sensitivity are discussed both through simulation and experiment for different filling factor variation, here Δf=0.0222 and Δf=0.0089. This scheme based on a “Peak-tracking chip” demonstrates a new technique for bioarray imaging using a simpler set-up that maintains high performance with cheap lenses, with down to Δn=2×10-5 RIU sensitivity for the highest sampling of Fano lineshapes. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Citation
Bougot-Robin, Kristelle, Shunbo Li, Weisheng Yue, L. Q. Chen, X. X. Zhang, W. J. Wen, and Henri Benisty. "Fano lineshapes of'Peak-tracking chip'spatial profiles analyzed with correlation analysis for bioarray imaging and refractive index sensing." In SPIE Microtechnologies, pp. 876703-876703. International Society for Optics and Photonics, 2013Publisher
SPIE-Intl Soc Optical EngConference/Event name
Integrated Photonics: Materials, Devices, and Applications IIae974a485f413a2113503eed53cd6c53
10.1117/12.2018316