Fiber In-Line Mach-Zehnder Interferometer Based on a Pair of Optical Fiber Diffraction Gratings

Optical fiber in-line Mach-Zehnder interferometer for strain and refractive index sensing is proposed based on a pair of multi-column diffraction gratings. In the device operation, part of the light traveling in the fiber core diffracted to the cladding region through the first set of multi-column d...

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Veröffentlicht in:IEEE photonics technology letters 2022-10, Vol.34 (20), p.1096-1099
Hauptverfasser: Gao, J. W., Xia, Q. K., Wang, D. N.
Format: Artikel
Sprache:eng
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Zusammenfassung:Optical fiber in-line Mach-Zehnder interferometer for strain and refractive index sensing is proposed based on a pair of multi-column diffraction gratings. In the device operation, part of the light traveling in the fiber core diffracted to the cladding region through the first set of multi-column diffraction gratings, and directed back into the fiber core by the second set of multi-column diffraction gratings after being reflected at the cladding-air interface. The rest of the light remains traveling along the core, and the two parts of light recombine and produce interference. Thus, the multi-column diffraction gratings pair essentially forms an optical fiber in-line Mach-Zehnder interferometer. The transmission spectra of different free spectral ranges can be obtained by controlling the separation of two set of multi-column diffraction gratings. The sensitivities achieved for strain and refractive index are ~−1.43 pm / \mu \varepsilon and 363.41 nm/RIU (refractive index unit), respectively. As the device has a low temperature sensitivity 8.03 pm/°C, the temperature cross sensitivity can be greatly reduced. Such a device is small in size, robust in structure, and convenient in operation, and has potential in photonic applications.
ISSN:1041-1135
1941-0174
DOI:10.1109/LPT.2022.3202923