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. 2018 May 8;18(5):1475.
doi: 10.3390/s18051475.

Manufacturing a Long-Period Grating with Periodic Thermal Diffusion Technology on High-NA Fiber and Its Application as a High-Temperature Sensor

Xiang Shen  1 , Bin Dai  2 , Yingbin Xing  3 , Luyun Yang  4 , Haiqing Li  5 , Jinyan Li  6 , Jingang Peng  7
Affiliations

Manufacturing a Long-Period Grating with Periodic Thermal Diffusion Technology on High-NA Fiber and Its Application as a High-Temperature Sensor

Xiang Shen et al. Sensors (Basel). .

Abstract

We demonstrated a kind of long-period fiber grating (LPFG), which is manufactured with a thermal diffusion treatment. The LPFG was inscribed on an ultrahigh-numerical-aperture (UHNA) fiber, highly doped with Ge and P, which was able to easily diffuse at high temperatures within a few seconds. We analyzed how the elements diffused at a high temperature over 1300 °C in the UHNA fiber. Then we developed a periodically heated technology with a CO₂ laser, which was able to cause the diffusion of the elements to constitute the modulations of an LPFG. With this technology, there is little damage to the outer structure of the fiber, which is different from the traditional LPFG, as it is periodically tapered. Since the LPFG itself was manufactured under high temperature, it can withstand higher temperatures than traditional LPFGs. Furthermore, the LPFG presents a higher sensitivity to high temperature due to the large amount of Ge doping, which is approximately 100 pm/°C. In addition, the LPFG shows insensitivity to the changing of the environment’s refractive index and strain.

Keywords: fiber optics; fiber optics sensor; high-temperature sensor; long period grating.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) The schematic illustration of the optical path in the LZM-100. (b) Formation of an LPFG on a UHNA-7 fiber with a CO2 laser splicer. (c) The structure of the LPFG on the UHNA-7 fiber. (d) The side image of the LPFG under a microscope.
Figure 2
Figure 2
(a) Transmission intensities of the LPFG as it forms (for an increasing number of pitches), and (b) the intensities of LPFGs with three different pitches.
Figure 3
Figure 3
Post-processing of the LPFG. (a) The center wavelength shifts with time and increasing temperature. (b) Comparison of the spectrum of the LPFG before and after heat treatment.
Figure 4
Figure 4
Variation of (a) the center wavelength of the LPFG and (b) its spectrum with temperature; and (c) the comparison with the spectra of the LPFG before and after high-temperature measurement.
Figure 5
Figure 5
The LPFG’s sensitivity of (a) the environment refractive index; and (b) strain.
Figure 6
Figure 6
Cross-section of an (a) unheated and (b) heated UHNA-7 fiber, measured with a microscope. (c) Side image of LPFG which shows the heated and unheated part.
Figure 7
Figure 7
Element distribution on the cross-section of the (a) unheated and (b) heated UHNA-7 fiber. (c) The refractive index profile of the unheated UHNA-7 fiber.
See this image and copyright information in PMC

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References

    1. Stephen W.J., Ralph P.T. Optical fibre long-period grating sensors: Characteristics and application. Meas. Sci. Technol. 2003;14:R49.
    1. Kakarantzas G., Dimmick T.E., Birks T.A., Le Roux R., Russell P.S.J. Miniature all-fiber devices based on CO2 laser microstructuring of tapered fibers. Opt. Lett. 2001;26:1137–1139. doi: 10.1364/OL.26.001137. - DOI - PubMed
    1. Vengsarkar A.M., Lemaire P.J., Judkins J.B., Bhatia V., Erdogan T., Sipe J.E. Long-period fiber gratings as band-rejection filters. J. Lightwave Technol. 1996;14:58–65. doi: 10.1109/50.476137. - DOI
    1. Kondo Y., Nouchi K., Mitsuyu T., Watanabe M., Kazansky P.G., Hirao K. Fabrication of long-period fiber gratings by focused irradiation of infrared femtosecond laser pulses. Opt. Lett. 1999;24:646–648. doi: 10.1364/OL.24.000646. - DOI - PubMed
    1. Savin S., Digonnet M.J.F., Kino G.S., Shaw H.J. Tunable mechanically induced long-period fiber gratings. Opt. Lett. 2000;25:710–712. doi: 10.1364/OL.25.000710. - DOI - PubMed

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