Relative humidity sensor with optical fiber Bragg gratings

Kronenberg, Pascal; Rastogi, Pramod K.; Giaccari, Philippe; Limberger, H.G.

doi:10.1364/ol.27.001385

Cited by 257 publications

(147 citation statements)

References 6 publications

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“…The wavelength change of the POFBG is largely introduced by the axial stress due to water induced swelling or shrinking in the fibre. This axial stress is proportional to the longitudinal expansion coefficient of the fibre, which is the contribution of both fibre core and cladding, depending on the material composition and the cross-section area [11]. The recorded time responses of 3 POFBGs with the outer diameters of 105 μm, 135 μm, and 190 μm, operated at the same conditions (input optical power, surrounding temperature and humidity), as shown in Fig.…”

Section: Influence Of Input Optical Powermentioning

confidence: 99%

An investigation into the wavelength stability of polymer optical fibre Bragg gratings

et al. 2012

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The inscription of Bragg gratings has been demonstrated in PMMA-based polymer optical fibre. The water affinity of PMMA can introduce significant wavelength change in a polymer optical fibre Bragg grating (POFBG). In polymer optical fibre losses are much higher than with silica fibre. Very strong absorption bands related to higher harmonics of vibrations of the C-H bond dominate throughout the visible and near infrared. Molecular vibration in substances generates heat, which is referred to as the thermal effect of molecular vibration. This means that a large part of the absorption of optical energy in those spectral bands will convert into thermal energy, which eventually drives water content out of the polymer fibre and reduces the wavelength of POFBG. In this work we have investigated the wavelength stability of POFBGs in different circumstances. The experiment has shown that the characteristic wavelength of a POFBG starts decreasing after a light source is applied to it. This decrease continues until equilibrium inside the fibre is established, depending on the initial water content inside the fibre, the surrounding humidity, the optical power applied, and the fibre size. Our investigation has shown that POFBGs operating at around 850 nm show much smaller wavelength reduction than those operating at around 1550 nm in the same fibre; POFBGs with different diameters show different changes; POFBGs powered by a low level light source, or operating in a very dry environment are least affected by this thermal effect.

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Section: Influence Of Input Optical Powermentioning

confidence: 99%

An investigation into the wavelength stability of polymer optical fibre Bragg gratings

et al. 2012

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“…here S RH and S T are sensitivity coefficients of humidity and temperature of the polyimide-coated FBG humidity sensor, respectively [16].…”

Section: Fbg Sensormentioning

confidence: 99%

“…When the polyimide resin is coated on the FBG sensor to form the moisture sensitive layer, this polyimide coating will undergo a volume expansion as the water molecules migrate into it, which directly induces a strain imposed on the FBG and in turn results in a proportional shift of the Bragg wavelength of the FBG sensor. Based on this sensing mechanism, the humidity measurements are carried out by directly reading this wavelength shift through spectrum analysis methods [9,16,31,36,[42][43][44][45].…”

Section: Introductionmentioning

confidence: 99%

Polyimide-Coated Fiber Bragg Grating Sensors for Humidity Measurements

Wang¹,

Fang²,

Huang³

2012

High Performance Polymers - Polyimides Based - From Chemistry to Applications

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Compared to the conventional mechanical and electrical/electronic humidity sensors, fiber-optic based humidity sensors [6,14], including silica glass fiber and polymer optical fiber (POF) based sensors [28, 46], demonstrate many unique advantages, such as small size and low weight, immunity to electromagnetic interference, corrosion resistance, potentials for remote operation and distributed sensing. In fiber-optic sensor family, the fiber grating

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“…Fiber Bragg Gratings (FBGs) have received more attention in the past decades due to their numerous strain [2][3], temperature [2], humidity [4][5] and acoustic [6][7] properties. Compared to other types of sensors, FBG sensors have demonstrated three major advantages.…”

Section: Introductionmentioning

confidence: 99%