Open AccessPolarized spectral combs probe optical fiber surface plasmons
Author(s) -
Christophe Caucheteur,
Valérie Voisin,
Jacques Albert
Publication year - 2013
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.003055
Subject(s) - optics , materials science , surface plasmon resonance , cladding (metalworking) , long period fiber grating , surface plasmon , fiber bragg grating , plasmon , cladding mode , optical fiber , localized surface plasmon , grating , refractive index , polarization (electrochemistry) , wavelength , surface plasmon polariton , optoelectronics , fiber optic sensor , polarization maintaining optical fiber , physics , chemistry , nanotechnology , nanoparticle , metallurgy
The high-order cladding modes of conventional single mode fiber come in semi-degenerate pairs corresponding to mostly radially or mostly azimuthally polarized light. Using tilted fiber Bragg gratings to excite these mode families separately, we show how plasmonic coupling to a thin gold coating on the surface of the fiber modifies the effective indices of the modes differently according to polarization and to mode order. In particular, we show the existence of a single "apolarized" grating resonance, with equal effective index for all input polarization states. This special resonance provides direct evidence of the excitation of a surface plasmon on the metal surface but also an absolute wavelength reference that allows for the precise localization of the most sensitive resonances in refractometric and biochemical sensing applications. Two plasmon interrogation methods are proposed, based on wavelength and amplitude measurements. Finally, we use a biotin-streptavidin biomolecular recognition experiment to demonstrate that differential spectral transmission measurements of a fine comb of cladding mode resonances in the vicinity of the apolarized resonance provide the most accurate method to extract information from plasmon-assisted Tilted fiber Bragg gratings, down to pM concentrations and at least 10(-5) refractive index changes.