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Sensors 2016, 16(5), 672;

Modeling of a Single-Notch Microfiber Coupler for High-Sensitivity and Low Detection-Limit Refractive Index Sensing

Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Author to whom correspondence should be addressed.
Academic Editors: Manuel Lopez-Amo, Jose Miguel Lopez-Higuera and Jose Luis Santos
Received: 28 February 2016 / Revised: 27 April 2016 / Accepted: 27 April 2016 / Published: 11 May 2016
(This article belongs to the Special Issue Optical Fiber Sensors 2016)
Full-Text   |   PDF [3038 KB, uploaded 11 May 2016]   |  


A highly sensitive refractive index sensor with low detection limit based on an asymmetric optical microfiber coupler is proposed. It is composed of a silica optical microfiber and an As2Se3 optical microfiber. Due to the asymmetry of the microfiber materials, a single-notch transmission spectrum is demonstrated by the large refractive index difference between the two optical microfibers. Compared with the symmetric coupler, the bandwidth of the asymmetric structure is over one order of magnitude narrower than that of the former. Therefore, the asymmetric optical microfiber coupler based sensor can reach over one order of magnitude smaller detection limit, which is defined as the minimal detectable refractive index change caused by the surrounding analyte. With the advantage of large evanescent field, the results also show that a sensitivity of up to 3212 nm per refractive index unit with a bandwidth of 12 nm is achieved with the asymmetric optical microfiber coupler. Furthermore, a maximum sensitivity of 4549 nm per refractive index unit can be reached while the radii of the silica optical microfiber and As2Se3 optical microfiber are 0.5 μm and a 0.128 μm, respectively. This sensor component may have important potential for low detection-limit physical and biochemical sensing applications. View Full-Text
Keywords: optical microfiber sensors; asymmetric coupler; low detection limit optical microfiber sensors; asymmetric coupler; low detection limit

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Zhang, J.; Shi, L.; Zhu, S.; Xu, X.; Zhang, X. Modeling of a Single-Notch Microfiber Coupler for High-Sensitivity and Low Detection-Limit Refractive Index Sensing. Sensors 2016, 16, 672.

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