Optical-fiber strain sensors with asymmetric etched structures

Vaziri, M.; Chen, Chin‐Lin

doi:10.1364/ao.32.006399

Cited by 20 publications

(15 citation statements)

References 8 publications

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“…5,6 Such stretchinduced microbends effectively enhance refractive index modulation in the CO 2 -laser-carved LPFGs, which is similar to the case of the microbend-induced LPFG. 5 Therefore, the refractive index modulation efficiency in the CO 2 -laser-carved LPFG is higher than that of the CO 2 -laser-induced LPFG without periodic grooves.…”

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confidence: 56%

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Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber

Wang

Jin

et al. 2006

Applied Physics Letters

104

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An asymmetric long period fiber grating ͑LPFG͒ with a large attenuation of −47.39 dB and a low insertion loss of 0.34 dB is fabricated by use of focused CO 2 laser beam to carve periodic grooves on one side of the optical fiber. Such periodic grooves and the stretch-induced periodic microbends can effectively enhance the refractive index modulation and increase the average strain sensitivity of the resonant wavelength of the LPFG to −102.89 nm/ m . The resonant wavelength and the peak attenuation of the LPFG can be tuned by ϳ12 nm and ϳ20 dB, respectively, by the application of a stretching force. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2360253͔ Long period fiber grating ͑LPFG͒ is one of the widely used passive optical fiber devices. Various LPFG fabrication techniques have been demonstrated, including ultraviolet laser irradiation, 1 CO 2 laser heat, 2,3 hydrofluoric acid etching corrugation, 4 and application of periodic microbend. 5 The strain sensitivity obtained for the CO 2 -laser-induced LPFGs without physical deformation is usually very low, only −0.45 nm/ m . 2,3 In this letter, a technique of fabricating asymmetric LPFG by use of focused CO 2 laser beam to carve periodic grooves on one side of the optical fiber is presented. The LPFGs obtained exhibit a large peak transmission attenuation of −47.39 dB and a low insertion loss of 0.34 dB. Moreover, the average strain sensitivity of resonant wavelength of the LPFG is increased to −102.89 nm/ m .Our experimental setup is shown in Fig. 1. A CO 2 laser ͑SYNRAD 48-1͒ with a maximum output power of 10 W, a light-emitting diode light source, and an optical spectrum analyzer ͑HP 70004A͒ were used. The optical fiber ͑Corning SMF-28͒ was situated in the focal plane of the CO 2 laser beam. One of the fiber ends was fixed and a small weight of ϳ5 g was used at the free end of the fiber to avoid the weight-induced macrobend and to provide a tensile strain in the fiber. The focused CO 2 laser beam scanned repeatedly for M times along the X direction at a location, corresponding to the first grating period, of the fiber via a two-dimensional optical scanner under the computer control. Then the laser beam was shifted by a grating period along the Y direction and scanned repeatedly for M times to generate the next grating period. This scanning and shifting process was carried out for N times ͑N is the number of grating periods͒ until the final grating period was created. The above mentioned process was repeated for K cycles until a high quality LPFG was produced. The repeated scanning of the focused CO 2 laser beam created a local high temperature in the fiber, which led to the gasification of SiO 2 on the surface of the fiber. As a result, periodic grooves were carved on the fiber as shown in Fig. 2. Such grooves induce periodic refractive index modulation along the fiber axis due to the photoelastic effect, thus creating a LPFG. The typical depth and width of the grooves obtained in our LPFGs were ϳ15 and ϳ50 m, respectively. The depth of the grooves dep...

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confidence: 56%

“…6 So periodic microbends will be observed when a CO 2 -laser-carved LPFG with asymmetric grooves is stretched, as shown in Fig. 6.…”

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confidence: 97%

Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber

Wang

Jin

et al. 2006

Applied Physics Letters

104

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“…The research by Vaziri et al [12] showed a good linearity for the coefficient of strain increased with an increase in the depth of grooves. Experiments in this paper showed the dissimilar conclusion that the absolute value of sensitivity may comply with the linearity for the depth of grooves, not the original sensitivity.…”

Section: Resultsmentioning

confidence: 92%

Scheme of optical fiber temperature sensor employing deep-grooved process optimization

Liu

Gaolin

et al. 2015

Photonic Sens

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Abstract:To optimize the optical fiber temperature sensor employing the deep-grooved process, a novel scheme was proposed. Fabricated by the promising CO 2 laser irradiation system based on the two-dimensional scanning motorized stage with high precision, the novel deep-grooved optical fiber temperature sensor was obtained with its temperature sensitivity of the transmission attenuation -0.107 dB/℃, which was 18.086 times higher than the optical fiber sensor with the normal depth of grooves while other parameters remained unchanged. The principal research and experimental testing showed that the designed temperature sensor measurement unit had the ability of high sensitivity in transmission attenuation and insensitivity to the wavelength, which offers possible applications in engineering.

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“…4, small lateral bends, i.e. periodic microbends, will be induced, resulting from the asymmetric structure, at each grooved section while the CO 2 -laser-induced LPFG with asymmetric grooves is stretched longitudinally [14,15]. As a result, additional refractive index perturbation is induced by the stretch-induced microbend in the grating due to the photoelastic effect, thus enhancing refractive index modulation in the CO 2 -laser-induced LPFG, which is similar to the case of the microbend-induced LPFG [16][17][18].…”

Section: Applying Tensile Strainmentioning

confidence: 99%

Post-treatment techniques for enhancing mode-coupling in long period fiber gratings induced by CO2 laser

Tang

Zhao

et al. 2015

Photonic Sens

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Two promising post-treatment techniques, i.e. applying tensile strain and rising temperature, are demonstrated to enhance the mode-coupling efficiency of the CO 2 -laser-induced long period fiber gratings (LPFGs) with periodic grooves. Such two post-treatment techniques can be used to enhance the resonant attenuation of the grating to achieve a LPFG-based filter with an extremely large attenuation and to tailor the transmission spectrum of the CO 2 -laser-induced LPFG after grating fabrication.

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Optical-fiber strain sensors with asymmetric etched structures

Cited by 20 publications

References 8 publications

Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber

Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber

Scheme of optical fiber temperature sensor employing deep-grooved process optimization

Post-treatment techniques for enhancing mode-coupling in long period fiber gratings induced by CO2 laser

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