Analysis of Fano-line shapes from agile resonant waveguide grating sensors using correlation techniques

K. Bougot-Robin; W. J. Wen; H. Benisty

doi:10.1117/12.2017563

3 May 2013 Analysis of Fano-line shapes from agile resonant waveguide grating sensors using correlation techniques

K. Bougot-Robin, W. J. Wen, H. Benisty

Proceedings Volume 8774, Optical Sensors 2013; 87741B (2013) https://doi.org/10.1117/12.2017563
Event: SPIE Optics + Optoelectronics, 2013, Prague, Czech Republic

Abstract

The asymmetric Fano resonance lineshape, 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. Correlation approach is robust to asymmetry of Fano lineshapes and allows more accurate determination than usual fitting options such as Gaussian or Lorentz shape fitting. Our findings are illustrated with resonance profiles from silicon nitride “chirped” RWGs operated at visible wavelengths. The scheme circumvents the classical but demanding spectral or angular scans: instead of varying angle or wavelength through fragile moving parts or special optics, a RWG structure parameter is varied. 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 plain images of these “pixelated” Fano profiles allows multiplex refractive index based sensing with a sensitivity down to 2×10^-5 RIU as demonstrated experimentally. 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.

Citation Download Citation

K. Bougot-Robin, W. J. Wen, and H. Benisty "Analysis of Fano-line shapes from agile resonant waveguide grating sensors using correlation techniques", Proc. SPIE 8774, Optical Sensors 2013, 87741B (3 May 2013); https://doi.org/10.1117/12.2017563

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
7 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Refractive index

Waveguides

Reflectivity

Sensors

Biological research

Biosensing

Shape analysis

Show All Keywords

Keywords/Phrases

Search In:

Publication Years