Plasmonic Optical Fiber Gratings Based on Few-Layer Ta2C MXenes for Refractive Index Sensing.

Tilted fiber Bragg grating (TFBG) is a widespread approach for developing refractive index (RI) sensors. The unique optoelectronic properties exhibited by MXene are expected to enhance the performance of TFBG-SPR sensors. In this study, a Ta2C coating appropriate for sensing was obtained by optimizing the photo-deposition time, which addressed the challenge of preparing large areas of MXene. The uniform coating of the few-layer Ta2C increases the wavelength sensitivity and FOM of the sensor to 229.5 nm/RIU and 2228.15 respectively. This significant enhancement was attributed to an ordered MXene phase of the grown Ta2C. The energy band theory verified the metallic nature of the Ta2C and the amplification effect on the RI response. Finite element analysis demonstrated that the stronger absorption band of Ta2C facilitated the generation of surface plasmon polariton. Based on the above benefits, the sensor detected melamine in milk with a detection limit of 7.9 ×10-9 M. The TFBG/Au/Ta2C sensor is a promising approach for biochemical analysis and trace detection.