Detection of organic aromatic compounds in paraffin by a long-period fiber grating optical sensor with optimized sensitivity

Allsop, Thomas D.P.; Zhang, Lin; Bennion, I.

doi:10.1016/s0030-4018(01)01131-2

Cited by 101 publications

(48 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1, forms the basis of a suite of sensors using LPGs, for example as a RI sensor [9], a chemical concentration sensor [10], a biochemical sensor [11], [12], a liquid level sensor and for tuneable spectral filters for various industrial production quality control [13]- [15]. These applications, however, are mostly limited by the requirement that the external RI needs to be smaller than that of the cladding.…”

Section: A Long Period Gratings For Sensing Applicationsmentioning

confidence: 99%

Analysis of the Characteristics of PVA-Coated LPG-Based Sensors to Coating Thickness and Changes in the External Refractive Index

et al. 2013

View full text Add to dashboard Cite

This is the accepted version of the paper.This version of the publication may differ from the final published version. Abstract-Recent research has shown that the transmission spectrum of a long period grating (LPG) written into an optical fiber is sensitive to the thickness and the refractive index (RI) of a thin layer deposited on it, a concept which forms the basis of a number of optical fiber sensors. The research reported herein is focused, in particular, on sensors of this type to create a design with an optimized thickness of the deposited layers of polyvinyl alcohol (PVA) on LPGs forming the basis of a highly sensitive probe. In creating such sensors, the dip-coating technique is used to minimize deleterious effects in the attenuation bands resulting from the inhomogeneity of the coated surface. In this paper, LPGs with different coating thicknesses are uniformly coated with thin layers of PVA and submerged in oils of known RI over the range from 1.30 to 1.70, to create effective RI probes. It is observed that when the coating thickness reaches a particular value that enables a substantial redistribution of the optical power within the overlay, a maximum sensitivity of the sensor can be achieved, even when the overlay has a RI higher than that of the cladding. Permanent repository link

show abstract

Section: A Long Period Gratings For Sensing Applicationsmentioning

confidence: 99%

Analysis of the Characteristics of PVA-Coated LPG-Based Sensors to Coating Thickness and Changes in the External Refractive Index

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The twofold increased sensitivity of these LPG devices for the index regime of 1.32 to 1.38 (at a thickness of ~0.7Pm) occurs as metal superimposed LPGs have cladding modes with a lower effective index compared with the bare fibre LPG, hence the maximum sensitivity of the attenuation band is achieved at a lower effective index of the surrounding medium. The spectral index sensitivity of this fibre device was calculated using the approach of references [2] and [7], where it was found that the "general sensitivity parameter" for the copper coated waveguide is greater than the bare waveguide for a given cladding mode order, but the spectral index sensitivity for both waveguides were approximately the same, see figures 9 and 10. Whilst the calculated index sensitivity does not explain the experimentally observed sensitivity, the differences in the "general sensitivity parameters" may offer an indication of the spectral behaviour of the copper-coated LPG device.…”

Section: Refractive Index Sensitivity Of the Copper Ringed Long Periomentioning

confidence: 99%

“…The study of LPGs has yielded many potential uses in the area of telecommunications and numerous sensing applications. This is because the mean wavelengths of the attenuation bands are influenced by strain, temperature, curvature and the refractive index of the surrounding medium [1][2][3][4][5][6][7][8][9]. In particular there has been strong interest in using long period gratings as chemical sensors [6,7,9], for example in the detection of organic aromatic compounds in paraffin [7].…”

Section: Introductionmentioning

confidence: 99%

“…This is because the mean wavelengths of the attenuation bands are influenced by strain, temperature, curvature and the refractive index of the surrounding medium [1][2][3][4][5][6][7][8][9]. In particular there has been strong interest in using long period gratings as chemical sensors [6,7,9], for example in the detection of organic aromatic compounds in paraffin [7]. Whilst the index sensitivity of most LPG based devices is greatest for solutions that have an index of approximately 1.44, which is good for various organic hydrocarbon compounds, there is a need to increase the sensitivity of these devices in aqueous solutions and for biochemical applications, where index values are typically from 1.333 to 1.380; for example the effective index of a cell is ~1.36 to 1.38 [10,11].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced spectral sensitivity of fibre long-period gratings to refractive index of aqueous solutions utilising copper patterned coatings

et al. 2006

Self Cite

View full text Add to dashboard Cite

A set of long period grating devices have been fabricated in photosensitive single mode fibre coated with a series of copper rings (period of 380Pm, 50% duty cycle and length of 4cm). The long period gratings were inscribed with a uniform UV-laser exposure across the entire length of the copper ring patterned coating. The devices ranged in copper thickness from 0.5Pm to 1.5Pm. In addition, a control long period grating was fabricated in the same type of fibre with the same period for comparison. The refractive index and temperature spectral sensitivity of these devices were investigated and it was found that the index and temperature sensitivity is a function of the thickness of the copper rings, as supported by theoretical modelling. Furthermore, the index sensitivity of these devices in the 1.333 index region is greater than the control long period grating. The patterned 0.5Pm coated long period grating gave a sensitivity of 'O/'n = -74 nm leading to a resolution of 1.4u10-3 compared to the control which had a sensitivity of 'O/'n = -32 nm with a resolution of 3.2u10 -3 in the index region of 1.320 to 1.380 (aqueous solution regime). This demonstrates a two fold increase in the sensitivity. This novel fibre long period grating device shows potential for increasing the resolution of measurements of the index of aqueous solutions.

show abstract

“…Long period gratings are currently the subject of considerable research interest due to their potential applications as filters and as sensing devices [3]. This study of the LPG attenuation bands has yielded many potential applications in the field of sensing through the dependence of the position of the attenuation bands on strain (ε), temperature (T), the refractive index of the surrounding medium (ns) and bending [4][5][6][7][8][9][10][11]. The spectral shift of the attenuation band arises from the phase matching condition of the LPG [3].…”

Section: Introductionmentioning

confidence: 99%

Characterisation of femtosecond laser inscribed long period gratings in photonic crystal fibre

et al. 2008

View full text Add to dashboard Cite

The use of high intensity femtosecond laser sources for inscribing fibre gratings has attained significant interest. The principal advantage of high-energy pulses is their ability for grating inscription in any material type without preprocessing or special core doping -the inscription process is controlled multi-photon absorption, void generation and subsequent local refractive index changes. The formation of grating structures in photonics crystal fibre has proven difficult, as the presence of holes within the fibre that allow wave-guidance impair and scatter the femtosecond inscription beam. Here we report on the consistent manufacture of long period gratings in endlessly single mode microstructure fibre and on their characterisation to external perturbations. Long period gratings are currently the subject of considerable research interest due to their potential applications as filters and as sensing devices, responsive to strain, temperature, bending and refractive index. Compared to the more mature fibre Bragg grating sensors, LPGs have more complex spectra, usually with broader spectral features. On the other hand they are intrinsically sensitive to bending and refractive index. Perhaps more importantly, the fibre design and choice of grating period can have a considerable influence over the sensitivity to the various parameters, for example allowing the creation of a bend sensor with minimal temperature cross-sensitivity. This control is not possible with FBG sensors. Here we compare the effects of symmetric and asymmetric femtosecond laser inscription.

show abstract

Detection of organic aromatic compounds in paraffin by a long-period fiber grating optical sensor with optimized sensitivity

Cited by 101 publications

References 5 publications

Analysis of the Characteristics of PVA-Coated LPG-Based Sensors to Coating Thickness and Changes in the External Refractive Index

Analysis of the Characteristics of PVA-Coated LPG-Based Sensors to Coating Thickness and Changes in the External Refractive Index

Enhanced spectral sensitivity of fibre long-period gratings to refractive index of aqueous solutions utilising copper patterned coatings

Characterisation of femtosecond laser inscribed long period gratings in photonic crystal fibre

Contact Info

Product

Resources

About