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Compact high-resolution FBG strain interrogator based on laser-written 3D scattering structure in flat optical fiber

Compact high-resolution FBG strain interrogator based on laser-written 3D scattering structure in flat optical fiber
Compact high-resolution FBG strain interrogator based on laser-written 3D scattering structure in flat optical fiber

We demonstrate a fiber Bragg grating (FBG) strain interrogator based on a scattering medium to generate stable and deterministic speckle patterns, calibrated with applied strain, which are highly dependent on the FBG back-reflection spectral components. The strong wavelength-dependency of speckle patterns was previously used for high resolution wavemeters where scattering effectively folds the optical path, but instability makes practical realization of such devices difficult. Here, a new approach is demonstrated by utilizing femtosecond laser-written scatterers inside flat optical fiber, to enhance mechanical stability. By inscribing 15 planes of pseudo-randomized nanovoids (714 × 500 voids per plane) as a 3D array in a 1 × 0.7 × 0.16 mm volume, the intrinsic stability and compactness of the device was improved. Operating as a wavemeter, it remained stable for at least 60 h with 45 pm resolution over the wavelength range of 1040–1056 nm. As a reflection mode FBG interrogator, after calibrating speckle patterns by applying tensile strain to the FBG, the device is capable of detecting microstrain changes in the range of 0–200 μϵ with a standard error of 4 μϵ , limited by the translation stage step size. All these characteristics make it an interesting technology for filling the niche of low-cost, high-resolution wavemeters and interrogators which offer the best available trade-off between resolution, compactness, price and stability.

flat fibre, FBG interrogator, Fiber Bragg grating, scattering matrix, singular value decomposition, Speckle pattern, speckle tracking, wavemeter
2045-2322
8805
Falak, Przemyslaw
f414a5d1-34e8-429d-8f9a-f203b6d83324
Lee, Timothy
beb3b88e-3e5a-4c3f-8636-bb6de8040fcc
Zahertar, Shahrzad
9e9db9c7-0e1e-4d50-99b8-af23e09ab6ae
Shi, Bo
82147c8a-5263-460b-a260-a863aab0874f
Moog, Bruno
fb647fef-2caa-44b3-8157-2b141f5d8cf5
Brambilla, Gilberto
815d9712-62c7-47d1-8860-9451a363a6c8
Holmes, Christopher
16306bb8-8a46-4fd7-bb19-a146758e5263
Beresna, Martynas
a6dc062e-93c6-46a5-aeb3-8de332cdec7b
Falak, Przemyslaw
f414a5d1-34e8-429d-8f9a-f203b6d83324
Lee, Timothy
beb3b88e-3e5a-4c3f-8636-bb6de8040fcc
Zahertar, Shahrzad
9e9db9c7-0e1e-4d50-99b8-af23e09ab6ae
Shi, Bo
82147c8a-5263-460b-a260-a863aab0874f
Moog, Bruno
fb647fef-2caa-44b3-8157-2b141f5d8cf5
Brambilla, Gilberto
815d9712-62c7-47d1-8860-9451a363a6c8
Holmes, Christopher
16306bb8-8a46-4fd7-bb19-a146758e5263
Beresna, Martynas
a6dc062e-93c6-46a5-aeb3-8de332cdec7b

Falak, Przemyslaw, Lee, Timothy, Zahertar, Shahrzad, Shi, Bo, Moog, Bruno, Brambilla, Gilberto, Holmes, Christopher and Beresna, Martynas (2023) Compact high-resolution FBG strain interrogator based on laser-written 3D scattering structure in flat optical fiber. Scientific Reports, 13 (1), 8805, [8805 (2023)]. (doi:10.1038/s41598-023-35708-1).

Record type: Article

Abstract

We demonstrate a fiber Bragg grating (FBG) strain interrogator based on a scattering medium to generate stable and deterministic speckle patterns, calibrated with applied strain, which are highly dependent on the FBG back-reflection spectral components. The strong wavelength-dependency of speckle patterns was previously used for high resolution wavemeters where scattering effectively folds the optical path, but instability makes practical realization of such devices difficult. Here, a new approach is demonstrated by utilizing femtosecond laser-written scatterers inside flat optical fiber, to enhance mechanical stability. By inscribing 15 planes of pseudo-randomized nanovoids (714 × 500 voids per plane) as a 3D array in a 1 × 0.7 × 0.16 mm volume, the intrinsic stability and compactness of the device was improved. Operating as a wavemeter, it remained stable for at least 60 h with 45 pm resolution over the wavelength range of 1040–1056 nm. As a reflection mode FBG interrogator, after calibrating speckle patterns by applying tensile strain to the FBG, the device is capable of detecting microstrain changes in the range of 0–200 μϵ with a standard error of 4 μϵ , limited by the translation stage step size. All these characteristics make it an interesting technology for filling the niche of low-cost, high-resolution wavemeters and interrogators which offer the best available trade-off between resolution, compactness, price and stability.

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Scientific_Reports_FF_Device_for_reviewers_12_04_2023 - Accepted Manuscript
Available under License Creative Commons Attribution.
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s41598-023-35708-1 - Version of Record
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More information

Accepted/In Press date: 22 May 2023
Published date: 31 May 2023
Additional Information: Funding Information: The authors would like to thank: Prof Francesco Poletti, Dr Thomas Bradley, Mr Nicholas White and Mr Glenn Topley for assistance with preform assembly and optical fiber drawing. This work was partially developed under EPSRC grants ‘Roll-2-Roll (R2R) manufacture of multilayer planar optics’ (EP/V053213/1), ‘Giant magneto-optic response in rare-earth doped glasses and manufacturing of related devices and sensors’ (EP/S013776/1) and ‘National Hub in High Value Photonic Manufacturing’ (EP/N00762X/1). Publisher Copyright: © 2023, The Author(s).
Keywords: flat fibre, FBG interrogator, Fiber Bragg grating, scattering matrix, singular value decomposition, Speckle pattern, speckle tracking, wavemeter

Identifiers

Local EPrints ID: 477242
URI: http://eprints.soton.ac.uk/id/eprint/477242
ISSN: 2045-2322
PURE UUID: 937992ad-d50a-48aa-8d0f-6c0a328d7ca7
ORCID for Przemyslaw Falak: ORCID iD orcid.org/0000-0002-2970-0700
ORCID for Timothy Lee: ORCID iD orcid.org/0000-0001-9665-5578
ORCID for Shahrzad Zahertar: ORCID iD orcid.org/0000-0001-6988-2345
ORCID for Bo Shi: ORCID iD orcid.org/0000-0003-0895-3052
ORCID for Gilberto Brambilla: ORCID iD orcid.org/0000-0002-5730-0499
ORCID for Christopher Holmes: ORCID iD orcid.org/0000-0001-9021-3760

Catalogue record

Date deposited: 01 Jun 2023 16:56
Last modified: 18 Mar 2024 02:27

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Contributors

Author: Przemyslaw Falak ORCID iD
Author: Timothy Lee ORCID iD
Author: Bo Shi ORCID iD
Author: Bruno Moog

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