Surface Plasmon Enhanced Fiber Sensor

Transmission spectra were simulated in this study for surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) based fiber sensor by finite difference time domain (FDTD) method. Distinct transmission properties were revealed as arising from the interference between optical field and excitation of SPR or LSPR. The transmission peak and dip positions were very sensitive when the sensor was immersed in the solution with different refractive indices. The sensitivity of the bare fiber sensor was about 259.4 nm/RIU, while that of the fiber coated with 50 nm thickness Au film was about 2000 nm/RIU. These results showed that the SPR based fiber can significantly enhance sensitivity. The sensitivity of LSPR based fiber sensor, in which the fiber was coated with periodic Au arrays, increased to 2500 nm/RIU. Interference structures were simulated to reveal the distribution of electric field in the fiber sensors. These devices can be applied to bio-chemical sensing and other related applications.