A high-sensitivity thermal sensing is demonstrated by coating a layer of polydimethylsiloxane (PDMS) on the surface of a silica toroidal microresonator on a silicon wafer. Possessing high-Q whispering gallery modes (WGMs), the PDMS-coated microresonator is highly sensitive to the temperature change of the surroundings. We find that, when the PDMS layer becomes thicker, the WGM experiences a transition from red- to blue-shift with temperature increasing due to the negative thermal-optic coefficient of PDMS. The measured sensitivity (0.151 nm/K) is one order of magnitude higher than pure silica microcavity sensors. The ultra-high resolution of the thermal sensor is also analyzed to reach 10-4 K.
@article{arxiv.1011.0254,
title = {On chip, high-sensitivity thermal sensor based on high-Q polydimethylsiloxane-coated microresonator},
author = {Bei-Bei Li and Qing-Yan Wang and Yun-Feng Xiao and Xue-Feng Jiang and Yan Li and Lixin Xiao and Qihuang Gong},
journal= {arXiv preprint arXiv:1011.0254},
year = {2015}
}