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Experimental Validation of the Sensitivity of Waveguide Grating Based Refractometric (Bio)sensors.

Gartmann TE, Kehl F - Biosensors (Basel) (2015)

Bottom Line: Despite the fact that the theoretical foundations of the sensitivity of waveguide grating based (bio)sensors are well-known, understood and their implications anticipated by the scientific community since several decades, to our knowledge, no prior publication has experimentally confirmed waveguide sensitivity for multiple film thicknesses, wavelengths and polarization of the propagating light.The effective refractive indices and the corresponding sensitivity were determined via the sensors' coupling angles at different cover refractive indices for transverse electric as well as transverse magnetic polarized illumination at various wavelengths in the visible and near-infrared.The theoretical sensitivity was calculated by solving the mode equation for a three layer waveguide.

View Article: PubMed Central - PubMed

Affiliation: CSEM Centre Suisse d'Electronique et de Microtechnique SA, Bahnhofstrasse 1, Landquart CH-7302, Switzerland. thomas.gartmann@csem.ch.

ABSTRACT
Despite the fact that the theoretical foundations of the sensitivity of waveguide grating based (bio)sensors are well-known, understood and their implications anticipated by the scientific community since several decades, to our knowledge, no prior publication has experimentally confirmed waveguide sensitivity for multiple film thicknesses, wavelengths and polarization of the propagating light. In this paper, the bulk refractive index sensitivity versus waveguide thickness of said refractometric sensors is experimentally determined and compared with predictions based on established theory. The effective refractive indices and the corresponding sensitivity were determined via the sensors' coupling angles at different cover refractive indices for transverse electric as well as transverse magnetic polarized illumination at various wavelengths in the visible and near-infrared. The theoretical sensitivity was calculated by solving the mode equation for a three layer waveguide.

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By atomic force microscopy (AFM) measured profile of the grating after (a) and before (b) deposition of ~300 nm Ta2O5, together with a topographical scan of the grating (c) after deposition. Due to the small aspect ratio of the grating (hg << Λ), the structure of the grating is mostly conserved also for thicker Ta2O5 layers.
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biosensors-05-00187-f004: By atomic force microscopy (AFM) measured profile of the grating after (a) and before (b) deposition of ~300 nm Ta2O5, together with a topographical scan of the grating (c) after deposition. Due to the small aspect ratio of the grating (hg << Λ), the structure of the grating is mostly conserved also for thicker Ta2O5 layers.

Mentions: Several samples were examined by atomic force microscopy (AFM) to measure the RMS surface roughness as well as to ensure the envisaged grating structure and confirm the conformity of the two corrugated interfaces S-F and F-C, which was inherently granted due to the grating’s small aspect ratio (hg << Λ) (Figure 4). This particular chip design with two different waveguide thicknesses is based on the WIOS sensor [19,20], a standard product at Optics Balzers, with the advantage of the production process being readily available, stable and well understood. Whereas the configuration with two adjacent waveguide regions with two different thicknesses are a prerequisite for the WIOS sensor, it was not a requirement for the measurements conducted in the framework of this study, but still beneficial, as two different thicknesses could be investigated at once.


Experimental Validation of the Sensitivity of Waveguide Grating Based Refractometric (Bio)sensors.

Gartmann TE, Kehl F - Biosensors (Basel) (2015)

By atomic force microscopy (AFM) measured profile of the grating after (a) and before (b) deposition of ~300 nm Ta2O5, together with a topographical scan of the grating (c) after deposition. Due to the small aspect ratio of the grating (hg << Λ), the structure of the grating is mostly conserved also for thicker Ta2O5 layers.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493545&req=5

biosensors-05-00187-f004: By atomic force microscopy (AFM) measured profile of the grating after (a) and before (b) deposition of ~300 nm Ta2O5, together with a topographical scan of the grating (c) after deposition. Due to the small aspect ratio of the grating (hg << Λ), the structure of the grating is mostly conserved also for thicker Ta2O5 layers.
Mentions: Several samples were examined by atomic force microscopy (AFM) to measure the RMS surface roughness as well as to ensure the envisaged grating structure and confirm the conformity of the two corrugated interfaces S-F and F-C, which was inherently granted due to the grating’s small aspect ratio (hg << Λ) (Figure 4). This particular chip design with two different waveguide thicknesses is based on the WIOS sensor [19,20], a standard product at Optics Balzers, with the advantage of the production process being readily available, stable and well understood. Whereas the configuration with two adjacent waveguide regions with two different thicknesses are a prerequisite for the WIOS sensor, it was not a requirement for the measurements conducted in the framework of this study, but still beneficial, as two different thicknesses could be investigated at once.

Bottom Line: Despite the fact that the theoretical foundations of the sensitivity of waveguide grating based (bio)sensors are well-known, understood and their implications anticipated by the scientific community since several decades, to our knowledge, no prior publication has experimentally confirmed waveguide sensitivity for multiple film thicknesses, wavelengths and polarization of the propagating light.The effective refractive indices and the corresponding sensitivity were determined via the sensors' coupling angles at different cover refractive indices for transverse electric as well as transverse magnetic polarized illumination at various wavelengths in the visible and near-infrared.The theoretical sensitivity was calculated by solving the mode equation for a three layer waveguide.

View Article: PubMed Central - PubMed

Affiliation: CSEM Centre Suisse d'Electronique et de Microtechnique SA, Bahnhofstrasse 1, Landquart CH-7302, Switzerland. thomas.gartmann@csem.ch.

ABSTRACT
Despite the fact that the theoretical foundations of the sensitivity of waveguide grating based (bio)sensors are well-known, understood and their implications anticipated by the scientific community since several decades, to our knowledge, no prior publication has experimentally confirmed waveguide sensitivity for multiple film thicknesses, wavelengths and polarization of the propagating light. In this paper, the bulk refractive index sensitivity versus waveguide thickness of said refractometric sensors is experimentally determined and compared with predictions based on established theory. The effective refractive indices and the corresponding sensitivity were determined via the sensors' coupling angles at different cover refractive indices for transverse electric as well as transverse magnetic polarized illumination at various wavelengths in the visible and near-infrared. The theoretical sensitivity was calculated by solving the mode equation for a three layer waveguide.

Show MeSH