Modeling of a long-period fiber-optic grating assisted surface Plasmon resonance refractive index sensor

A fiber-optic refractive index sensor assisted surface Plasmon resonance of metal dielectric layer around a long-period fiber-optic grating with hollow fiber core has been proposed and comprehensively analyzed. Its operation principle is based on the efficient energy transfer between the fiber waveguide mode and the co-directional surface Plasmon waves excited with a long-period fiber-optic grating properly designed by the light refracted through the interface between the waveguide area and the metal dielectric film. The long-period fiber-optic grating is fabricated on a waveguide area of a specially designed fiber-optic with hollow fiber core. Simulations have been carried out in coupled mode theory of fiber-optic gratings in the wavelength ranges from 1500 to 1600nm, and for sensing characteristics of refractive index. Unlike a previous proposed fiber Bragg grating fabricated on this kind of fiber, t the sensitivity of the long-period fiber-optic grating SPR refractive index sensor is much higher than that of a FBG in the same structure. The proposed long-period fiber-optic refractive index sensor assisted surface Plasmon resonance is compact, light weight, and highly sensitive with a large sensing range.