Effect of femtosecond laser parameters on the SPR sensing characteristics of tilted fiber Bragg grating refractive index sensors

In this study, we systematically investigate the combined impact of key manufacturing parameters—including tilt angle, grating length, and inscribed line length—on the optical properties and sensing performance of tilted fiber Bragg gratings (TFBGs) fabricated using the femtosecond laser direct writing technique, with particular emphasis on their role in enabling and optimizing metal surface plasmon resonance (SPR) excitation for enhanced sensing applications. The capacity of TFBGs to excite the SPR effect presents a new opportunity to develop optical sensors with improved sensitivity and selectivity, requiring a comprehensive understanding of how fabrication details affect their performance. This study verifies the effects of different key fabrication parameters (including tilt angle, grating length, and inscribed line length) on spectral features and their relationship with SPR excitation efficiency through theoretical analysis and experimental studies. The findings of this study are poised to serve as a comprehensive reference for subsequent research endeavors aimed at exploiting the unique properties of TFBG-SPR sensors.