Reducing the temperature sensitivity of SOI waveguide-based biosensors

Kristinn B. Gylfason; Albert Mola Romero; Hans Sohlström

doi:10.1117/12.922263

10 May 2012 Reducing the temperature sensitivity of SOI waveguide-based biosensors

Kristinn B. Gylfason, Albert Mola Romero, Hans Sohlström

Proceedings Volume 8431, Silicon Photonics and Photonic Integrated Circuits III; 84310F (2012) https://doi.org/10.1117/12.922263
Event: SPIE Photonics Europe, 2012, Brussels, Belgium

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.

Citation Download Citation

Kristinn B. Gylfason, Albert Mola Romero, and Hans Sohlström "Reducing the temperature sensitivity of SOI waveguide-based biosensors", Proc. SPIE 8431, Silicon Photonics and Photonic Integrated Circuits III, 84310F (10 May 2012); https://doi.org/10.1117/12.922263

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