Refractive-sensitivity of mechanical long-period fiber grating in side-hole fiber

The refractive index sensor for use of a stress MLPG in a side-hole singlemode fiber is proposed. The principle of operation is based on using of a long-period grating that is made by pressing a plate with periodic grooves against a short length of side-hole fiber. The resonance wavelengths are shifted as the two side-holes of the fiber core were filled with the different the refractive index liquids. The results show that it is more sensitive than that of the conventional long-period fiber gratings.