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Proceedings Paper

Reducing the temperature sensitivity of SOI waveguide-based biosensors
Author(s): Kristinn B. Gylfason; Albert Mola Romero; Hans Sohlström
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Paper Abstract

Label-free photonic biosensors fabricated on silicon-on-insulator (SOI) can provide compact size, high evanescent field strength at the silicon waveguide surface, and volume fabrication potential. However, due to the large thermo optic coefficient of water-based biosamples, the sensors are temperature-sensitive. Consequently, active temperature control is usually used. However, for low cost applications, active temperature control is often not feasible. Here, we use the opposite polarity of the thermo-optic coefficients of silicon and water to demonstrate a photonic slot waveguide with a distribution of power between sample and silicon that aims to give athermal operation in water. Based on simulations, we made three waveguide designs close to the athermal point, and asymmetric integrated Mach- Zehnder interferometers for their characterization. The devices were fabricated on SOI with a 220 nm device layer and 2 μm buried oxide, by electron beam lithography of hydrogen silsesquioxane (HSQ) resist, and etching in a Cl2/HBr/O2/He plasma. With Cargile 50350 fused silica matching oil as top cladding, the group index of the three guides varies from 1.9 to 2.8 at 1550 nm. The temperature sensitivity of the devices varied from -70 to -160 pm/K under the same conditions. A temperature sensitivity of -2 pm/K is projected with water as top cladding.

Paper Details

Date Published: 10 May 2012
PDF: 15 pages
Proc. SPIE 8431, Silicon Photonics and Photonic Integrated Circuits III, 84310F (10 May 2012); doi: 10.1117/12.922263
Show Author Affiliations
Kristinn B. Gylfason, Royal Institute of Technology (Sweden)
Albert Mola Romero, Royal Institute of Technology (Sweden)
Univ. of Barcelona (Spain)
Hans Sohlström, Royal Institute of Technology (Sweden)

Published in SPIE Proceedings Vol. 8431:
Silicon Photonics and Photonic Integrated Circuits III
Laurent Vivien; Seppo K. Honkanen; Lorenzo Pavesi; Stefano Pelli, Editor(s)

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