https://doi.org/10.1140/epjd/s10053-026-01219-7
Research - Photon
Taper-based Sagnac interferometer sensor with sensitivity enhancement based on multiple polymer microspheres
1
College of Physics Science and Technology, Yangzhou University, 225002, Yangzhou, China
2
National Laboratory of Solid State Microstructures, Nanjing University, 210093, Nanjing, China
3
China Ship Development and Design Center, 430064, Wuhan, China
a
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Received:
5
November
2025
Accepted:
22
June
2026
Published online:
2
July
2026
Abstract
Environmental monitoring of temperature and humidity shows vitally important due to its abundant applications in the monitoring of industrial and agricultural fields. In this paper, a compact Sagnac interferometer (SI) is fabricated by twisting a tapered fiber. High-order mode interference in the silica-based SI induces its only response on the temperature with the sensitivity of 8.1 pm/oC. Furthermore, by adding multiple polymer microspheres on the Sagnac loop, the fiber-optic sensitivities both in the temperature sensing and humidity sensing are greatly improved because of the high thermal-humidity effect of polymer material and the enhanced multi-mode interference in the SI. Different numbers of UV-glue microspheres are sequentially attached to the Sagnac loop to detailedly analyze their influence on the temperature sensitivity, finally obtaining the highest value of 50.8 pm/oC for the case of 2 microspheres. Similarly, the humidity sensitivity can be up to 102.6 pm/%RH.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2026
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
