Fiber Bragg Grating-Tunable Delay Line Interferometer for High Precision Vibration Sensing

A combination of optical Fiber Bragg Gratings (FBGs) and a Tunable Delay Line Interferometer (TDLI) is proposed for capturing vibration signals amidst inherent, undeniable noises. The proposed system leverages the adjustable Free Spectral Range (FSR) of the TDLI to significantly enhance the sensitivity of FBG-based sensors, particularly for distinguishing extremely close superposition vibration frequencies in various frequency ranges. The tuning technique for FSR adjustment in FBG peak power modulation, designed to achieve accurate measurement signals with diminished noise when FBG wavelength shift occurs, is revealed. Incorporating Free-Space Optics (FSOs) into the vibration sensing framework further enhances system flexibility by facilitating wireless, high-speed vibration data transmission in scenarios where direct fiber connections are impractical, such as remote or dynamic environments. Moreover, the system embeds deep learning algorithms that enable high-accuracy recognition of vibration frequencies without the need for denoising techniques. The coalescences of FBG-TDLI and FSO technologies, integrated with deep learning techniques, create a highly precise, adaptable, and efficient vibration sensing system. The findings underscore this approach’s potential to redefine vibration sensing applications in critical infrastructure, power plants, and industrial systems, offering a new paradigm for precision monitoring in challenging operational conditions.