Optimizing Parameters and Applications of Femtosecond Laser Technology in Fiber Bragg Grating Manufacture

Abstract

Fiber Bragg Grating (FBG) sensors have garnered extensive attention for their pivotal role in diverse domains, including strain, pressure, hydroacoustics, and temperature monitoring, especially within the ambit of the Internet of Things (IoT). The femtosecond laser point-by-point fabrication methodology stands out in this context, primarily for its flexibility in altering FBG periods through precise control of the fiber’s movement velocity. This adaptability facilitates the creation of FBGs with varied periodicities, significantly broadening their application spectrum. A notable aspect of FBG sensors is their sensitivity to temperature variations, which manifest as changes in both the grating pitch and the refractive index of the FBG. These alterations consequently induce shifts in the FBG’s reflection and transmission spectra. Specifically, temperature fluctuations lead to a discernible drift in the central wavelength of the light reflected by the Bragg grating. This wavelength drift is linearly proportional to the temperature change, rendering it a reliable metric for assessing both the magnitude and rate of temperature variations. Experimental framework was centered around the femtosecond laser point-by-point fabrication technique for FBG creation. Within this setup, we delved into four critical factors influencing the spectral quality of the FBGs: grating length, periodicity, laser energy, and grating position. By meticulously adjusting these parameters, we aimed to optimize the performance and applicability of FBG sensors in real-world IoT scenarios.