Open AccessM-line spectroscopy on mid-infrared Si photonic crystals for fluid sensing and chemical imaging
Author(s) -
Ventsislav Lavchiev,
Bernhard Jakoby,
Ursula Hedenig,
Th. Grille,
James M. R. Kirkbride,
Grant A. D. Ritchie
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.000262
Subject(s) - materials science , photonic crystal , optics , refractive index , prism , absorption (acoustics) , spectroscopy , photonics , optoelectronics , attenuation coefficient , absorption spectroscopy , physics , quantum mechanics , composite material
The presented work demonstrates the design and characterization of Si-based photonic crystal waveguides operating as an evanescent wave absorption sensor in the mid-IR range λ = 5-6 µm. The photonic crystal structure is fabricated in a Si slab upon a thin Si(3)N(4)/TEOS/Si(3)N(4) membrane. M-line spectroscopy is used to verify the presence of guided waves. Different fillings of the photonic crystal holes have been realized to avoid sample residuals in the holes and, at the same time, to obtain spectral tuning of the structures by modification of the refractive index contrast with the photonic background. The chip displays sensitivity to fluid droplets in two-prism experiments. The output signal is quantitatively related to the fluid's absorption coefficient thereby validating the experimental method.