Optical fiber long-period grating sensors

Bhatia, Vikram; Vengsarkar, Ashish M.

doi:10.1364/ol.21.000692

Cited by 1,082 publications

(412 citation statements)

References 3 publications

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“…Refractive index sensing is important for biological and chemical applications since a number of substances can be detected through measurements of the refractive index. [2][3][4][8][9][10][11][12][13] For normal FBGs, removal of the fiber cladding is required to increase the evanescent field interaction with the surrounding environment. This concept has been demonstrated using D-shaped fiber and sidepolished fiber.…”

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confidence: 99%

Highly sensitive fiber Bragg grating refractive index sensors

Liang

Huang

et al. 2005

Applied Physics Letters

580

254

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We combine fiber Bragg grating ͑FBG͒ technology with a wet chemical etch-erosion procedure and demonstrate two types of refractive index sensors using single-mode optical fibers. The first index sensor device is an etch-eroded single FBG with a radius of 3 m, which is used to measure the indices of four different liquids. The second index sensor device is an etch-eroded fiber Fabry-Pérot interferometer ͑FFPI͒ with a radius of ϳ1.5 m and is used to measure the refractive indices of isopropyl alcohol solutions of different concentrations. Due to its narrower resonance spectral feature, the FFPI sensor has a higher sensitivity than the FBG sensor and can detect an index variation of 1.4ϫ 10 −5 . Since we can measure the reflection signal, these two types of sensors can be fabricated at the end of a fiber and used as point sensors. Since the early 1990s, fiber Bragg grating ͑FBG͒ sensors have been intensively developed due to their many desirable advantages such as the small size, absolute measurement capability, immunity to electromagnetic interference, wavelength multiplexing, and distributed sensing possibilities. [1][2][3][4][5] Thus far, the FBG sensors' capability to measure physical quantities such as the temperature, strain, pressure, etc., has been studied extensively. [2][3][4][5][6][7][8] However, the use of FBG sensors for detection of environmental refractive index change has not been fully explored. Refractive index sensing is important for biological and chemical applications since a number of substances can be detected through measurements of the refractive index. [2][3][4][8][9][10][11][12][13] For normal FBGs, removal of the fiber cladding is required to increase the evanescent field interaction with the surrounding environment. This concept has been demonstrated using D-shaped fiber and sidepolished fiber. 9,11,12 In both cases, the strength and durability of the sensor were greatly reduced. Special fiber was also needed, which would raise the costs and limit the possible applications. Long-period fiber gratings have also been demonstrated to have high sensitivity to the refractive index of the ambient media, 2,3,13-15 however, their multiple resonance peaks and broad ͑typically tens of nanometers͒ transmission resonance features limit the measurement accuracy and their multiplexing capabilities. 9 In addition, the relatively long length of the grating limits their application as point sensor devices.In this letter, we first demonstrate a single etch-eroded FBG sensor using standard single-mode telecommunication fiber ͑Corning SMF-28͒. Fiber Fabry-Pérot interferometers ͑FFPIs͒ have also been widely used as sensors. 2,3,16,17 Compared to a single FBG, the FFPI sensors possess narrower resonance peaks and are more desirable for high accuracy wavelength measurement. 2,3,9,18 To that end we propose and demonstrate an etch-eroded FFPI sensor formed by two FBGs. The FFPI sensor is used to measure the refractive index of isopropyl alcohol ͑IPA͒ solutions of different concentrations, exhibiting the capabi...

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confidence: 99%

Highly sensitive fiber Bragg grating refractive index sensors

Liang

Huang

et al. 2005

Applied Physics Letters

580

254

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“…The temperature coefficient for LPG B (+0.0595 nm/ o C) is one order of magnitude lower that that for LPG A (-0.2569 nm/ o C). Hence, LPG B is less affected by 5 temperature variations and can therefore be used for purposes, which require the LPG to remain unaffected by small changes in temperature.…”

Section: Positive and Negative Temperature Responsesmentioning

confidence: 99%

“…Hence, loss bands or resonance bands are observed in the transmission spectrum. The transmission spectra of LPGs have been shown to be sensitive to changes in index of refraction of the medium surrounding the fibre cladding (ambient refractive index) in the vicinity of the LPG [4][5][6] and also to changes in the ambient temperature [7]. Changes in the coupling wavelengths from the core modes to the various cladding modes due to changing ambient refractive indices using indexmatching gels have been reported in [8].…”

Section: Introductionmentioning

confidence: 99%

Temperature characterisation of long‐period gratings for sensor applications

O'Flaherty¹,

Ghassemlooy²,

Mangat³

et al. 2004

Micro & Optical Tech Letters

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“…Numerous techniques are available for fabricating LPFGs. Approaches that have been demonstrated include periodic local heating of the fiber using a CO/CO 2 laser [4,5] or electric arc discharge [6,7]. Fabrication techniques for mechanically induced LPFGs have also been reported [8, 9, 10].…”

Section: Introductionmentioning

confidence: 99%

Temperature sensing using an optical time domain reflectometer and mechanical long-period fiber gratings fabricated from a heat-shrinkable tube

Ohashi

Miyoshi

2017

IEICE ComEX

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We develop a simple temperature sensing using an optical time domain reflectometer (OTDR) and a mechanical long-period fiber grating (LPFG) fabricated from a heat-shrinkable tube and a metric screw. The resonance loss of the fabricated LPFG is strongly dependent on temperature as temperature-dependent heat-shrinkage of the tube produces a change in the pressure applied to the fiber. In our proposed temperature sensor, the LPFG insertion loss due to a change in the pressure applied to the fiber is measured using an OTDR with a resonance wavelength. Both singlepoint and multi-point temperature sensing is successfully demonstrated experimentally. Keywords: long period fiber gratings, optical time domain reflectometer, temperature sensing Classification: Sensing References[1] S. Nam, C. Zhan, J. Lee, C. Hahn, K. Reichard, P. Ruffin, K.-L. Deng, and S.Yin, "Bend-insensitive ultra short long-period gratings by the electric arc method and their applications to harsh environment sensing and communication," Opt. Express, vol.

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Optical fiber long-period grating sensors

Cited by 1,082 publications

References 3 publications

Highly sensitive fiber Bragg grating refractive index sensors

Highly sensitive fiber Bragg grating refractive index sensors

Temperature characterisation of long‐period gratings for sensor applications

Temperature sensing using an optical time domain reflectometer and mechanical long-period fiber gratings fabricated from a heat-shrinkable tube

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