This study aims to propose a method for adjusting loss peak in the spectrum of long period fiber grating fabricated with CO 2 laser by applying tension with some weight to make the loss peak suitable for a multi-point temperature sensor under a high temperature environment. This method could achieve an increase of 5.3 dB in the value of loss peak by loading the fiber with a weight of 150 g. Furthermore, it was found that the method had a minimal influence on the temperature sensitivity of the long period fiber grating in the range varying from room temperature to 800°C.

The first-order Raman spectra of sintered body-centered BaWO4 crystalline are measured at room temperature. The phonon dispersion curves of BaWO4 are calculated on the basis of a rigid-ion model using the measured frequency values. The temperature dependence of the phonon specific heat capacity, and the elastic constants of BaWO4 are calculated using one-phonon density of states and three acoustic phonon frequencies obtained from phonon dispersion curves, respectively.

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