Effects from detuning the resonant coupling between fiber gratings and localized surface plasmons

In this work, we demonstrate the effect of detuning the resonant coupling between a long period grating and the plasmonic band of gold nanoparticles on the device sensitivity. In an intensity coded configuration, the sensitivity was measured at 568.12 nm and 598.62 nm, for surroundings refractive indexes ranging from 1.3629 to 1.4184. A comparison between the responses of the two dips centered at these wavelengths resulted in a sensitivity enhancement of about 17 times for the dip localized close to the center of the localized surface plasmon resonance.