Mechanically induced long-period fiber grating in side-hole single-mode fiber for temperature and refractive sensing

The inscription of a long-period grating in a side-hole single-mode fiber for sensing application is demonstrated. The grating is made by pressing a plate with a periodic groove against a short section of length of a side-hole single-mode fiber. Its strength and wavelength of the cladding-mode resonant can be tuned over 15 dB and 6.2 nm, respectively, by varying the ambient temperature of the grating. The refractive index sensitivity and the polarization dependence of the MPLG are also investigated.