We propose and study an optical microfiber coupler (OMC) sensor working near the turning point of effective group index difference between the even supermode and odd supermode to achieve high refractive index (RI) sensitivity. Theoretical calculations reveal that infinite sensitivity can be obtained when the measured RI is close to the turning point value. This diameter-dependent turning point corresponds to the condition that the effective group index difference equals zero. To validate our proposed sensing mechanism, we experimentally demonstrate an ultrahigh sensitivity of 39541.7 nm/RIU at a low ambient RI of 1.3334 based on an OMC with the diameter of 1.4 μm. An even higher sensitivity can be achieved by carrying out the measurements at RI closer to the turning point. The resulting ultrasensitive RI sensing platform offers a substantial impact on a variety of applications from high performance trace analyte detection to small molecule sensing.
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Ultrasensitive optical microfiber coupler based sensors operating near the turning point of effective group index difference
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5 September 2016
Research Article|
September 06 2016
Ultrasensitive optical microfiber coupler based sensors operating near the turning point of effective group index difference
Kaiwei Li;
Kaiwei Li
1School of Electrical and Electronic Engineering,
Nanyang Technological University
, Singapore 639798, Singapore
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Ting Zhang;
Ting Zhang
1School of Electrical and Electronic Engineering,
Nanyang Technological University
, Singapore 639798, Singapore
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Guigen Liu;
Guigen Liu
2Department of Electrical and Computer Engineering,
University of Nebraska-Lincoln
, Lincoln, Nebraska 68588-0511, USA
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Nan Zhang;
Nan Zhang
1School of Electrical and Electronic Engineering,
Nanyang Technological University
, Singapore 639798, Singapore
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Mengying Zhang;
Mengying Zhang
1School of Electrical and Electronic Engineering,
Nanyang Technological University
, Singapore 639798, Singapore
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a)
Author to whom correspondence should be addressed. Electronic mail: WEI.LEI@ntu.edu.sg
Appl. Phys. Lett. 109, 101101 (2016)
Article history
Received:
May 21 2016
Accepted:
July 28 2016
Citation
Kaiwei Li, Ting Zhang, Guigen Liu, Nan Zhang, Mengying Zhang, Lei Wei; Ultrasensitive optical microfiber coupler based sensors operating near the turning point of effective group index difference. Appl. Phys. Lett. 5 September 2016; 109 (10): 101101. https://doi.org/10.1063/1.4961981
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