Surface Plasmon Resonance Based On Multi-angel Tilted Fiber Bragg Grating For Highly Sensitive And Wide Range Refractive Index Measurement

Surface-plasmon resonance (SPR), which results from the strong sensitivity of the plasmon-propagation constant to the permittivity of a nanoscale layer of material on a metal surface, is an exquisitely sensitive technique to detect chemical and biochemical changes occurring between molecules. In this work, we propose and demonstrate an SPR sensor based on a multi-angle tilted fiber Bragg grating (TFBG) coated by a 50 nm-thickness gold film for refractive index (RI) measurement. Experimental results show that wide range of RI, from 1.15 to 1.43, can be detected using the proposed SPR sensor, with sensitivity of 523.41 nm/RIU (refractive index unit). In addition, with designed as a probe, through coating a gold film as a reflection mirror in the cleaved end downstream of the grating, the length of the entire sensor is only 2 cm, making it easy to insert into the media for biochemical measurements.