Optimization of Fiber Bragg Grating Sensor for Enhanced Sensitivity and Accurate Measurement

Abstract

Sensor technology is transforming more rapidly to fulfill the needs of modern healthcare standards. Conventional electronic sensors are used for monitoring various biological parameters. These conventional sensors are based on electrical detection mechanisms and have several limitations. Conventional electronic sensors are prone to noise and electromagnetic interference and give inaccurate measurements in noisy environment. The optical fiber-based sensors are more promising than the conventional sensors due to their many advantages. Fiber Bragg Grating sensors are one of the emerging optical fiber-based sensors. FBG sensors are more suitable in biomedical measurement due to their small size and lightweight. Also, FBG sensors offer higher sensitivity than electronic sensors due to their high immunity to electromagnetic interference. FBG reflects the specific wavelength from grating structure known as Bragg wavelength. The strength of reflected signal is known as reflectivity. The unwanted wavelengths reflected along the Bragg wavelength are known as side lobe levels which contribute to the noise. High reflectivity and low side lobe levels are desirable for accurate measurements. The design of FBG sensors is crucial to achieve the desired sensing performance. The grating parameters affect reflectivity and side lobe levels. In this work the effect of grating length on reflectivity and side lobe levels is investigated to determine optimum grating length. The optimized grating length is necessary to obtain desired reflectivity and side lobe levels for precise measurements.

Introduction

The text explains the role of optical fiber sensors, especially Fiber Bragg Grating (FBG) sensors, in modern healthcare applications supported by technologies like AI, IoT, and machine learning. These advanced sensors are highlighted as more suitable than conventional electronic sensors because they are compact, lightweight, highly sensitive, immune to electromagnetic interference, and capable of multiplexing—making them ideal for medical monitoring and smart healthcare systems.

An FBG sensor works on the principle of Bragg reflection, where specific wavelengths of light are reflected while others pass through. The reflected wavelength, called the Bragg wavelength, depends on the refractive index and grating period. Key performance factors include reflectivity and side lobe levels (SLL), which affect measurement accuracy and noise.

The study also presents a simulation analysis using the OPTIGRATING tool to examine how grating length affects sensor performance. Results show that increasing grating length (from 5 mm to 50 mm) increases both reflectivity and side lobe levels. While higher reflectivity improves signal strength, it also raises noise (SLL), meaning an optimal grating length is required for accurate and reliable performance.

In summary, the text demonstrates that FBG sensors are highly effective for medical applications, but their performance depends on careful optimization of design parameters—especially grating length—to balance reflectivity and signal noise for precise healthcare monitoring.

Conclusion

FBG sensor is most promising in sensing applications due to their high sensitivity and high immunity to electromagnetic interference. FBG sensor design optimization is essential for desired performance in medical sensing application. The grating length, grating period and modulation index plays crucial role to obtain desired reflectivity and side lobe levels. In this work effect of grating length is shown on the reflectivity and side lobe levels. The obtained simulation results show that reflectivity and sidelobe levels increases with length. High reflectivity and low side lobe levels is desirable for precise sensing performance. Hence FBG sensor grating length should be optimum and carefully selected to obtain high reflectivity and low side lobe level. The apodization technique can be employed to reduce side lobe levels. Optimum grating length with apodization techniques can give high reflectivity and low sidelobe levels. This optimised FBG sensor will provide high sensitivity and accurate measurements in biomedical sensing applications.

References

[1] Marceddu et al, (2023). “Comprehensive Visualization of Data Generated by Fiber Bragg Grating Sensors,”. IEEE Access, 11. pp.121945 – 121955, 2023. [2] Hameed K. et al, “An Intelligent IoT based Healthcare system using fuzzy Nural Networks,” Scientific Programming, pp.1-15, December 2020. [3] Mohameda et al, “Characterization of Fiber Bragg Grating for applications in Nuclear Research Reactors,” Egyptian Journal for Engineering Sciences and Technology, vol.27, pp.23-29, 2019. [4] A. Naguib et al, “Performance evaluation and enhancement of apodized fiber Bragg grating for dispersion compensation,” AIP Advances, pp. 1-17, 2021. [5] R. Arumugam et al, “Novel Apodized Fiber Bragg Grating applied for Medical Sensors: Performance Investigation,”, Computer modelling in Engineering and Science, pp.301-323, September 2022.

Copyright

Copyright © 2026 Santosh Jotiram Jagatap, Ashok Jetawat , Saurabh Mehta, Jayshree Jain, Saurabh Mehta. 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.