Investigating the Spectral Response of Fiber Bragg Grating for Strain Sensor Applications

Abstract

The optical fibre sensor (OFS) has become quite well-known and prominent in the sensor technology industry. It is often used to react to outputs from other systems, like those in industrial, monitoring, and chemical analysis applications, and to detect changes in the environment. A Bragg reflector starts to grow and transmit all other wavelengths while a short section of optical fibre with a specific wavelength is reflected with light in a device called a Fibre Bragg Grating. The current study focuses on the evolving characteristics and behaviours of strain and temperature sensors operating on Fibre Bragg Gratings (FBG) through software modelling. This work\'s primary goal is to investigate the characteristics and behaviour of strain sensor that are used with fibre bragg gratings. A strain sensor can be used to determine the strain in an object whose resistance changes when force is applied.

Introduction

I. INTRODUCTION

A fiber-optic sensor is one that processes extrinsic sensor signals that are transmitted from the far sensor to the electronics, in addition to acting as an intrinsic sensor. An optical fibre consists of three parts: the coating, the cladding, and the core. The cladding layer was originally made of a dielectric material and has an index of refraction of n2. The index of refraction of the cladding material is less than that of the core material.[1]. sensors made of optical fibre that have a very broad bandwidth, are resilient against electromagnetic interference, and can function well in environments with high pressure, high temperatures, and poisonous materials.[2] The fibre Bragg grating sensor, also called Fibre Bragg Grating, is one of the most intriguing developments in optical fibre sensing technology. It is frequently employed in many SHM paradigms and has the ability to multiplex.[3] A Fibre Bragg Grating is a sensor with a distinct personality to adhere to. For instance, when the fibre is compacted, the strain is calculated using the Fibre Bragg Grating. This is caused by the distortion of the optical fibre, which alters the time adjustment of the microstructure. Affectability of the temperature-sensitive material is also intrinsic to a fibre Bragg grating. The temperature sensor used in the Fibre Bragg Grating, where the thermo-optic coefficient and the thermal-expansion coefficient cause the Bragg wavelength to shift as a result of a change in refractive index, is comparable to the strain sensors to which the single-point sensors belong and preserves the features of small size, solidity, peak accuracy, and elasto-optic (optical strain).[4] Various studies on Fibre Bragg Grating (FBG) have been carried out in the last few years by various researchers who have employed simulation to use Fibre Bragg Grating as a strain and temperature sensor. The refractive index and the grating period are the two primary results of Fibre Bragg Grating. In order to better understand the implications of Fibre Bragg Grating, this study discusses Fibre Bragg Grating and focuses on numerical theoretical demonstration and simulation using MATLAB.

Fibre Bragg Grating (FBG) have shown a great potential advantage in biomedical application over the past ten years [5] due to their prominent characteristics, which include their extremely small size, light weight, immunity to electromagnetic interference (EMI), electrical neutrality, and ability to be easily embedded into a structure without having any effects on the mechanical properties of the object under investigation[6][7].Fibre Bragg Grating was used as a photoacoustic (PA)detection method to detect the existence of tumours because of its capacity to transform the absorbed energy entirely into heat without producing PA signals caused by scattering particles[7]. Because it combines light contrast and ultrasonic resolution, the photoacoustic approach is unique[8]. This technique is used in tumour diagnosis because of its benefits, which include noninvasiveness, high detection sensitivity, and the ability to identify small element sizes[9],[10].

A sensor can be made out of specifically constructed optical fibre. In a tiny portion of the fibre, the core refractive index of the optical fibre intended for sensor applications differs from that of the conventional fibre core and cladding [11]. Usually, a periodic structure is introduced in that tiny portion of the optical fibre core. Fibre Bragg Gratings (FBG) are the name given to this region of the fibre core because it reflects specific wavelengths of light. When a dielectric waveguide's properties are regularly altered, the effective refractive index of the guide is also periodically altered [12],[13].

Alternatively, when a DBR is a structure composed of multiple, alternating layers of materials with variable refractive indices. The Bragg wavelength shift of Fibre Bragg Gratings determines the sensitivity of FBG-based sensors. Encoded in the fibre core segment, the FBG is a periodic wavelength scale alteration of the refractive index. Bragg gratings reflect light at a particular wavelength that meets the Bragg condition. This reflection in a grating occurs when forward and back propagation modes couple at a specific wavelength [14]. The coupling coefficient of the modes is highest when the specific condition, such as the Bragg condition, between the vectors of the light waves and the vector number of the grating, is satisfied.

Conclusion

In conclusion , this study has successfully accomplished every one of its stated goals. This study suggested simulating the behaviours and properties of fibre bragg gratings as temperature and strain sensors. This simulation can be used to examine performance, identify traits and behaviour, and assess how well the temperature and strain sensors work. The current work for this simulation created model for the temperature and strain sensors in the Fibre Bragg Grating was successfully analysed using MATLAB. The strain and temperature sensors of the Fibre Bragg Grating sensing system were simulated and coded for this research project using MATLAB software. This simulation can be used to analyse the behaviour, characteristics, and performance of fibre bragg gratings. Among the properties are the strain, temperature, and spectrum reflectivity for varying refractive index changes as well as grating length. The variations in grating length and refractive index were used in this simulation to examine these traits and behaviours.According to the simulation, strain is produced when a fiber\'s length deviates from its initial length. In the simulation, the increase in strain has an impact on the increase in Bragg wavelength shift.

References

[1] Fidanboylu, K. A., & Efendioglu, H. S. (2009, May). Fiber optic sensors and their applications. In 5th International Advanced Technologies Symposium (IATS’09) (Vol. 6, pp. 2-3) [2] Sidek, O., & Afzal, M. H. B. (2011, September). A review paper on fiber-optic sensors and application of PDMS materials for enhanced performance. In 2011 IEEE Symposium on Business. [3] Engineering and Industrial Applications (ISBEIA) (pp. 458-463). IEEE. Ye, X. W., Ni, Y. Q., & Yin, J. H. (2013). Safety monitoring of railway tunnel construction using Fiber Bragg Grating sensing technology. Advances in Structural Engineering, 16(8), 1401-1409 [4] E. Al-Fakih, N. A. Abu Osman, and F. R. Mahamd Adikan, “The Use of Fiber Bragg Grating Sensors in Biomechanics and Rehabilitation Applications: The State-of-the-Art and Ongoing Research Topics,” Sensors, vol. 12, no. 12, pp. 12890–12926, 2012. [5] T. Fink, Q. Zhang, W. Ahrens, and M. Han, “Study of ?-phase-shifted, fiber Bragg gratings for ultrasonic detection,” Fiber Opt. Sensors Appl. IX, vol. 8370, no. 7, pp. 1–7, 2012. [6] G. Wild and S. Hinckley, “Optical Fibre Bragg Gratings for Acoustic Sensors,” Int. Congr. Acoust., no. August, pp. 1–7, 2010. [7] A. Yarai and T. Nakanishi, “Fiber Bragg grating applied pulsed photoacoustic detection technique for online monitoring concentration of liquid,” J. Acoust. Soc. Am., vol. 123, no. 5, p. 3285, 2008. [8] C. Li and L. V Wang, “Photoacoustic tomography and sensing in biomedicine,” Phys. Med. Biol., vol. 54, no. 19, pp. R59–R97, 2009. [9] M. Xu and L. V. Wang, “Photoacoustic imaging in biomedicine,” Rev. Sci. Instrum., vol. 77, no. 4, p. 041101, 2006. [10] J. Xia, J. Yao, and L. V Wang, “Photoacoustic Tomography?: Principles and Advances,” Prog. eletromagnic Res., vol. 147, no. May, pp. 1–22, 2014. [11] E.Udd, Fiber Optic Sensors: An Introduction for Engineerings and Scientists (John Wiley and Sons, New York, 1991). [12] A.Cusano, A. Cutolo and M. Giordano, “Fiber Bragg Gratings Evanescent Wave Sensors: A View Back and RecentAdvancements”, Sensors, Springer-Verlag Berlin Heidelberg, 2008. [13] K.O.Hill and G. Meltz, “Fiber Bragg Grating Technology Fundamentals and Overview”, Journal of Lightwave Technology, Vol. 15,No. 8, August 1997. [14] G.P. Agrawal, Fiber-Optic Communication Systems, (John Wiley & Sons, 2002). [15] P. Fomitchov and S. Krishnaswamy, “Response of a fiber Bragg grating ultrasonic sensor,” Opt. Eng., vol. 42, no. 4, pp. 956–963, 2003. [16] M. A. Othman, M. M. Ismail, H. A. Sulaiman, et.al., “An Analysis of 10 Gbits / s Optical Transmission System using Fiber Bragg Grating ( FBG ),” IOSR J. Eng., vol. 2, no. 7, pp. 55–61, 2012. [17] https://www.fiberoptics4sale.com/blogs/archive-posts/95046406-what-is-fiber-bragg-grating [18] https://tempsens.com/blog/fiber-bragg-grating-based-sensors

Copyright

Copyright © 2023 Muhammad Arif Bin Jalil. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.