Demodulation of a tilted fibre Bragg grating transmission signal using α-shape modified Delaunay triangulation

Fazzi, Luigi; Groves, Roger M.

doi:10.1016/j.measurement.2020.108197

Cited by 19 publications

(16 citation statements)

References 34 publications

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“…In the original version, the method was based on determining the maxima and minima of the cladding mode comb to determine the normalised area occupied by the cladding mode [ 15 ]. The more precise version uses the Delaunay triangulation method [ 16 , 17 ]. These methods belong to the group that uses information about changes in the transmission coefficient for the entire range of the cladding modes.…”

Section: Methods Of Tfbg Spectra Analysismentioning

confidence: 99%

Single- and Double-Comb Tilted Fibre Bragg Grating Refractive Index Demodulation Methods with Fourier Transform Pre-Processing

Cięszczyk

Skorupski

Panas

2022

Sensors

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The development of fibre optic sensors for measuring the refractive index is related to the creation of new periodic structures and demodulation algorithms for the measured spectrum. Recently, we proposed a double-comb Tilted fibre Bragg grating (DCTFBG) structure. In this article, we analyse such a structure for measuring the refractive index in comparison to a single classical structure. Increasing the number of modes causes a significant change in the Fourier spectrum of optical spectra. For the purpose of data pre-processing, we propose the Fourier Transform as a filtering method in the frequency domain. Then, we analyse separately the band-filtered optical spectra for several frequency ranges. For quantitative analysis, we use algorithms that use quantitative changes in the transmission, i.e., the method of the envelope and the length of the spectrum contour. We propose the use of the Hilbert transform as the envelope method. The second type of algorithms used are methods determining the shift of spectrum features along the wavelength axis. The method of determining the centre of gravity of the area bounded by the envelope and the maximum of the second derivative of the smoothed cumulative spectrum contour length is proposed here. Using the developed methods, the measurement resolution was achieved at the level of 2 × 10−5 refractive index unit.

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Section: Methods Of Tfbg Spectra Analysismentioning

confidence: 99%

Single- and Double-Comb Tilted Fibre Bragg Grating Refractive Index Demodulation Methods with Fourier Transform Pre-Processing

Cięszczyk

Skorupski

Panas

2022

Sensors

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“…These issues are sometimes avoided by the use of pre-calibrated wavelength sweeping detection systems [197], or spectral "envelope" detection methods where individual resonance amplitude and wavelength fluctuations are averaged out [198][199][200][201][202]. When the measured transfer function of a sensor device in its initial (or rest) state can be simulated with a certain measurable accuracy, any change in the device state due to a "sensing event" can be traced back quantitatively to the cause of the change by varying those changes in the model until it fits the new measured state of the device.…”

Section: 6g Sensing In Multimodal Systems With Fiber Gratingsmentioning

confidence: 99%

Mode-division and spatial-division optical fiber sensors

et al. 2022

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The aim of this paper is to provide a comprehensive review of mode-division and spatial-division optical fiber sensors, mainly encompassing interferometers and advanced fiber gratings. Compared with their single-mode counterparts, which have a very mature field with many highly successful commercial applications, multimodal configurations have developed more recently with advances in fiber device fabrication and novel mode control devices. Multimodal fiber sensors considerably widen the range of possible sensing modalities and provide opportunities for increased accuracy and performance in conventional fiber sensing applications. Recent progress in these areas is attested by sharp increases in the number of publications and a rise in technology readiness level. In this paper, we first review the fundamental operating principles of such multimodal optical fiber sensors. We then report on the theoretical formalism and simulation procedures that allow for the prediction of the spectral changes and sensing response of these sensors. Finally, we discuss some recent cutting-edge applications, mainly in the physical and (bio)chemical fields. This paper provides both a step-by-step guide relevant for non-specialists entering in the field and a comprehensive review of advanced techniques for more skilled practitioners.

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“…In this work, only weakly TFBG were used because the special behaviour of the different peaks makes the weakly tilted FBG most suitable as a sensor for three-parameter sensing applications [11]. Figure 2 shows the internal structure of a weakly tilted FBG, where the tilt angle θ, the grating period Λ G along the OF axis and the nominal grating period Λ = Λ G cosθ are defined.…”

Section: Tfbg Theory and Influence Of The Surrounding Rimentioning

confidence: 99%

“…This range includes the maximum refractometry sensitivity range (1.40-1.46) of the TFBG, and furthermore demonstrates that the sensor was able to function even at higher RIs (>1.46), where all the cladding modes should have been irradiated out of the OF. This is possible, as part of the light continues to be irradiated externally, while some cladding modes return to be reflected internally towards the OF core where they are coupled [11]. Previous work that studied the TFBG sensor as a refractometer [3,12,[20][21][22], did not take this RI range into account during their analysis.…”

Section: Stability Of the α-Shape Modified Delaunay Demodulation Techniquementioning

confidence: 99%

“…Exploiting these demodulation techniques, the TFBG sensing ability toward the surrounding RI variation has been investigated in several applications, such as the monitoring of the cure degree of the resin during composite manufacturing [4,5], the microfluidic rate [6] and in chemical and biochemical fields [7][8][9][10]. However, since these previous demodulation techniques suffer certain drawbacks and limitations, in a previous work [11], we developed a new demodulation approach based on Delaunay triangulation (D-T) to obtain the surrounding RI value from the envelope area of the cladding modes.…”

Section: Introductionmentioning

confidence: 99%

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Refractometric Properties of a TFBG Sensor Demodulated Using α-Shape Modified Delaunay Triangulation

Fazzi

Groves

2021

Optics

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In our previous research, a novel demodulation technique based on α-shape Delaunay triangulation (D-T) was developed to obtain the refractive index of the medium surrounding the optical fibre using the envelope of the cladding peaks from the spectrum of the tilted fibre Bragg grating (TFBG) sensor. This technique was demonstrated to be efficient, easy to implement, powerful, faster than the previous ones and applicable for real-time measurements. In this paper, a deep parametric analysis of the resolution, repeatability and accuracy of the D-T demodulation technique for a TFBG refractometer sensor is performed and presented. The spectral properties of the TFBG sensor as a refractometer are explored using the same demodulation technique. Specifically, supposing the use of the TFBG as a two-parameter optical sensor, the influence of the strain on the envelope area is analysed, and the measurement stability regarding the external RI is reported. Then, the cladding resonance peaks in the spectrum are observed experimentally as the TFBG undergoes partial immersion in a defined refractive index liquid. This last experiment allowed a better understanding the evolution of the TFBG transmission spectrum when the Bragg gratings were partially surrounded by a medium with a different RI.

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Demodulation of a tilted fibre Bragg grating transmission signal using α-shape modified Delaunay triangulation

Cited by 19 publications

References 34 publications

Single- and Double-Comb Tilted Fibre Bragg Grating Refractive Index Demodulation Methods with Fourier Transform Pre-Processing

Single- and Double-Comb Tilted Fibre Bragg Grating Refractive Index Demodulation Methods with Fourier Transform Pre-Processing

Mode-division and spatial-division optical fiber sensors

Refractometric Properties of a TFBG Sensor Demodulated Using α-Shape Modified Delaunay Triangulation

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