Dual-Core Fiber-Based Interferometer for Detection of Gas Refractive Index

We demonstrate a dual-core fiber-based Mach–Zehnder interferometer that could be used for precise detection of variations in refractive indices of gaseous samples. The fiber used here have a solid germanium-doped silica core and an air core that allows gases to flow through. Coherent laser beams are...

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Bibliographic Details
Published in:Photonics 2020-12, Vol.7 (4), p.111
Main Authors: Chen, Haijin, Hu, Xuehao, He, Meifan, Yu, Qianqing, Lian, Zhenggang, Yang, Zicheng, Wang, Heng, Qu, Hang
Format: Article
Language:English
Subjects:
Cores
Fabrication
fiber optics sensors
Gases
Germanium
Interference fringes
interferometer
Laser beams
Lasers
Mach-Zehnder interferometers
microstructured fibers
Optics
Photodiodes
Polymers
Refractivity
Sensors
Silica
Silicon dioxide
Variation
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Summary:We demonstrate a dual-core fiber-based Mach–Zehnder interferometer that could be used for precise detection of variations in refractive indices of gaseous samples. The fiber used here have a solid germanium-doped silica core and an air core that allows gases to flow through. Coherent laser beams are coupled to the two cores, respectively, and thus excite guiding modes thereby. Interferogram would be produced as the light transmitted from the dual cores interferes. Variations in refractive index of the hollow core lead to variations in phase difference between the modes in the two cores, thus shifting the interference fringes. The fringe shifts can be then interrogated by a photodiode together with a narrow slit in front. The resolution of the sensor was found to be ~1 × 10−8 RIU, that is comparable to the highest resolution obtained by other fiber sensors reported in previous literatures. Other advantages of our sensor include very low cost, high sensitivity, straightforward sensing mechanism, and ease of fabrication.
ISSN:2304-6732
2304-6732
DOI:10.3390/photonics7040111