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Proceedings Paper

Temperature sensors and refractometers using liquid-core waveguide structures monolithically integrated in silica-on-silicon
Author(s): Patrick Dumais; Claire L. Callender; Julian P. Noad; Christopher J. Ledderhof
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Paper Abstract

Integrated optofluidic devices have many potential applications for on-chip analysis and sensing. The fabrication of single-mode liquid-core waveguides in an integrated format allows the implementation of robust and very sensitive interferometers that combine long optical paths (on the cm scale) with small volumes (less than a nanoliter). We have demonstrated the monolithic integration of microchannels and liquid-core waveguides with planar silica lightwave circuits, which allows a number of refractometer devices to be implemented. Of these, we demonstrate experimentally a monolithic Mach-Zehnder interferometer (MZI) comprising a 20 mm-long liquid-core waveguide. The liquid-core waveguide is quasi single mode at 1550 nm when filled with a liquid of nominal index of ~1.47 (such as toluene or an index matching fluid). In these conditions, the output of the MZI is a pure cosine function, as a function of a linear progression of the refractive index of the liquid medium. Furthermore, the high contrast ratio experimentally observed in the output function allows a precise monitoring of refractive index changes by tracking the position of the transmission minimum in the spectral domain. Refractive index variations can be measured to a precision on the order of 4x10-6. The large differential in thermo-optic coefficients between liquid media and silica allows the structure to function as a temperature sensor with a precision on the order of 10-2 degrees Celsius. The measurement of the spectral fringe spacing of the interferometer response allows absolute-value measurements of temperature and refractive index.

Paper Details

Date Published: 12 August 2008
PDF: 11 pages
Proc. SPIE 7099, Photonics North 2008, 70991Y (12 August 2008); doi: 10.1117/12.804593
Show Author Affiliations
Patrick Dumais, Communications Research Ctr. Canada (Canada)
Claire L. Callender, Communications Research Ctr. Canada (Canada)
Julian P. Noad, Communications Research Ctr. Canada (Canada)
Christopher J. Ledderhof, Communications Research Ctr. Canada (Canada)


Published in SPIE Proceedings Vol. 7099:
Photonics North 2008

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